diff --git a/code/__DEFINES/dcs/signals.dm b/code/__DEFINES/dcs/signals.dm
index c74a8cdb05..8706e96562 100644
--- a/code/__DEFINES/dcs/signals.dm
+++ b/code/__DEFINES/dcs/signals.dm
@@ -185,27 +185,6 @@
 
 #define COMSIG_MOB_SPELL_CAN_CAST "mob_spell_can_cast"			//from base of /obj/effect/proc_holder/spell/can_cast(): (spell)
 
-#define COMSIG_MOB_ACTION_SKILL_MOD "mob_action_skill_mod"		//from base of /datum/skill_holder/action_skills_mod() : (proc args list, list/mod_values)
-	#define ACTION_SKILL_MOD_SKILL 1 //redundancy.
-	#define ACTION_SKILL_MOD_VALUE 2
-	#define ACTION_SKILL_MOD_THRESHOLD 3
-	#define ACTION_SKILL_MOD_IS_MULTI 4
-	//other mod values, kept separate from the args
-	#define MOD_VALUES_SKILL_MOD 1
-
-#define COMSIG_MOB_ITEM_ACTION_SKILLS_MOD "mob_item_action_skills_mod"	//from base of /datum/skill_holder/item_action_skills_mod() : (proc args list, mod_values)
-	#define ITEM_SKILLS_MOD_ITEM 1 //redundancy
-	#define ITEM_SKILLS_MOD_VALUE 2
-	#define ITEM_SKILLS_MOD_FLAGS 3
-	#define ITEM_SKILLS_MOD_BAD_FLAGS 4
-	#define ITEM_SKILLS_MOD_IS_MULTI 5
-	//other mod values, kept separate from the args
-	#define MOD_VALUES_ITEM_SKILLS_SUM 1
-	#define MOD_VALUES_ITEM_SKILLS_DIV 2
-	#define MOD_VALUES_ITEM_SKILLS_CHECKED 3
-
-#define COMSIG_MOB_SKILL_GET_AFFINITY "mob_skill_get_affinity"	//from base of /datum/skill_holder/get_skill_affinity(): (skill_path, list/return_value)
-
 // /mob/living signals
 #define COMSIG_LIVING_REGENERATE_LIMBS "living_regenerate_limbs"	//from base of /mob/living/regenerate_limbs(): (noheal, excluded_limbs)
 #define COMSIG_LIVING_RESIST "living_resist"					//from base of mob/living/resist() (/mob/living)
diff --git a/code/__DEFINES/skills/defines.dm b/code/__DEFINES/skills/defines.dm
index 73be86e128..9127b4e3dd 100644
--- a/code/__DEFINES/skills/defines.dm
+++ b/code/__DEFINES/skills/defines.dm
@@ -20,9 +20,7 @@
 
 // Standard values for job starting skill affinities
 
-#define STARTING_SKILL_AFFINITY_SURGERY_MEDICAL			1.2
-
-#define STARTING_SKILL_AFFINITY_WIRING_ENGI_ROBO		1.2
+#define STARTING_SKILL_AFFINITY_DEF_JOB		1.2
 
 // Standard values for skill gain (this is multiplied by affinity)
 
@@ -75,3 +73,26 @@
 #define DORF_SKILL_COMPETENT	3
 #define DORF_SKILL_EXPERT		8
 #define DORF_SKILL_MASTER		12
+
+/// Skill modifier defines and flags.
+#define MODIFIER_SKILL_VALUE		(1<<0)
+#define MODIFIER_SKILL_AFFINITY 	(1<<1)
+#define MODIFIER_SKILL_LEVEL		(1<<2)
+///makes the skill modifier a multiplier, not an addendum.
+#define MODIFIER_SKILL_MULT			(1<<3)
+///Sets the skill to the defined value if lower than that. Highly reccomended you don't use it with MODIFIER_SKILL_MULT.
+#define MODIFIER_SKILL_VIRTUE		(1<<4)
+///Does the opposite of the above. combining both effectively results in the skill being locked to the specified value.
+#define MODIFIER_SKILL_HANDICAP		(1<<5)
+///Makes it untransferred by mind.transfer_to()
+#define MODIFIER_SKILL_BODYBOUND	(1<<6)
+///Adds the difference of the current value and the value stored at the time the modifier was added to the result.
+#define MODIFIER_SKILL_ORIGIN_DIFF	(1<<7)
+
+#define MODIFIER_TARGET_VALUE		"value"
+#define MODIFIER_TARGET_LEVEL		"level"
+#define MODIFIER_TARGET_AFFINITY	"affinity"
+
+///Ascending priority defines.
+#define MODIFIER_SKILL_PRIORITY_DEF 50
+#define MODIFIER_SKILL_PRIORITY_MAX 100 //max priority, meant for job/antag modifiers so they don't null out any debuff
diff --git a/code/__DEFINES/skills/helpers.dm b/code/__DEFINES/skills/helpers.dm
index 23669b3739..1a39dbd9e0 100644
--- a/code/__DEFINES/skills/helpers.dm
+++ b/code/__DEFINES/skills/helpers.dm
@@ -6,3 +6,25 @@
 //More experience value getter macros
 #define GET_STANDARD_LVL(lvl) XP_LEVEL(STD_XP_LVL_UP, STD_XP_LVL_MULTI, lvl)
 #define GET_DORF_LVL(lvl) DORF_XP_LEVEL(DORF_XP_LVL_UP, DORF_XP_LVL_MULTI, lvl)
+
+#define IS_SKILL_VALUE_GREATER(path, existing, new_value) GLOB.skill_datums[path].is_value_greater(existing, new_value)
+
+#define SANITIZE_SKILL_VALUE(path, value) GLOB.skill_datums[path].sanitize_value(value)
+
+///Doesn't automatically round the value.
+#define SANITIZE_SKILL_LEVEL(path, lvl) clamp(lvl, 0, GLOB.skill_datums[path].max_levels)
+
+/**
+  * A simple universal comsig for body bound skill modifiers.
+  * Technically they are still bound to the mind, but other signal procs will take care of adding and removing the modifier
+  * from/to new/old minds.
+  */
+#define ADD_SKILL_MODIFIER_BODY(mod, body) \
+	mod.RegisterSignal(body, COMSIG_MOB_ON_NEW_MIND, /datum/skill_modifier.proc/on_mob_new_mind, TRUE)
+
+///Macro used when adding generic singleton skill modifiers.
+#define ADD_SINGLETON_SKILL_MODIFIER(mind, path, id) \
+	if(!GLOB.skill_modifiers[id]){\
+		new path(id)\
+	};\
+	mind.add_skill_modifier(id ? "[path]&[id]" : path)
\ No newline at end of file
diff --git a/code/__HELPERS/_lists.dm b/code/__HELPERS/_lists.dm
index ad977ec493..38c2439019 100644
--- a/code/__HELPERS/_lists.dm
+++ b/code/__HELPERS/_lists.dm
@@ -37,6 +37,7 @@
 	* TYPECONT: The typepath of the contents of the list
 	* COMPARE: The object to compare against, usualy the same as INPUT
 	* COMPARISON: The variable on the objects to compare
+	* COMPTYPE: How the current bin item to compare against COMPARE is fetched. By key or value.
 	*/
 #define BINARY_INSERT(INPUT, LIST, TYPECONT, COMPARE, COMPARISON, COMPTYPE) \
 	do {\
diff --git a/code/_onclick/item_attack.dm b/code/_onclick/item_attack.dm
index f0b38f994d..ccbfab6b43 100644
--- a/code/_onclick/item_attack.dm
+++ b/code/_onclick/item_attack.dm
@@ -118,11 +118,11 @@
 		bad_flag |= SKILL_COMBAT_MODE //blacklist combat skills.
 	if(I.used_skills && user.mind)
 		if(totitemdamage)
-			totitemdamage = user.mind.skill_holder.item_action_skills_mod(I, totitemdamage, I.skill_difficulty, SKILL_ATTACK_OBJ, bad_flag)
+			totitemdamage = user.mind.item_action_skills_mod(I, totitemdamage, I.skill_difficulty, SKILL_ATTACK_OBJ, bad_flag)
 		for(var/skill in I.used_skills)
 			if(!(I.used_skills[skill] & SKILL_TRAIN_ATTACK_OBJ))
 				continue
-			user.mind.skill_holder.auto_gain_experience(skill, I.skill_gain)
+			user.mind.auto_gain_experience(skill, I.skill_gain)
 	if(totitemdamage)
 		visible_message("<span class='danger'>[user] has hit [src] with [I]!</span>", null, null, COMBAT_MESSAGE_RANGE)
 		//only witnesses close by and the victim see a hit message.
@@ -163,11 +163,11 @@
 	if(!user.mind || !I.used_skills)
 		return
 	if(.)
-		. = user.mind.skill_holder.item_action_skills_mod(I, ., I.skill_difficulty, SKILL_ATTACK_MOB, bad_flag)
+		. = user.mind.item_action_skills_mod(I, ., I.skill_difficulty, SKILL_ATTACK_MOB, bad_flag)
 	for(var/skill in I.used_skills)
 		if(!(I.used_skills[skill] & SKILL_TRAIN_ATTACK_MOB))
 			continue
-		user.mind.skill_holder.auto_gain_experience(skill, I.skill_gain)
+		user.mind.auto_gain_experience(skill, I.skill_gain)
 
 /mob/living/carbon/pre_attacked_by(obj/item/I, mob/living/user)
 	. = ..()
@@ -216,7 +216,7 @@
 		. *= STAM_COST_NO_COMBAT_MULT
 		bad_flag |= SKILL_COMBAT_MODE
 	if(used_skills && user.mind)
-		. = user.mind.skill_holder.item_action_skills_mod(src, ., skill_difficulty, flags, bad_flag, FALSE)
+		. = user.mind.item_action_skills_mod(src, ., skill_difficulty, flags, bad_flag, FALSE)
 
 /// How long this staggers for. 0 and negatives supported.
 /obj/item/proc/melee_stagger_duration(force_override)
diff --git a/code/controllers/subsystem/moods.dm b/code/controllers/subsystem/moods.dm
deleted file mode 100644
index f6b6ffcb40..0000000000
--- a/code/controllers/subsystem/moods.dm
+++ /dev/null
@@ -1,4 +0,0 @@
-PROCESSING_SUBSYSTEM_DEF(mood)
-	name = "Mood"
-	flags = SS_NO_INIT | SS_BACKGROUND
-	priority = 20
diff --git a/code/datums/components/mood.dm b/code/datums/components/mood.dm
index 23a81716b8..6ce7842273 100644
--- a/code/datums/components/mood.dm
+++ b/code/datums/components/mood.dm
@@ -1,3 +1,4 @@
+#define ECSTATIC_SANITY_PEN -1
 #define SLIGHT_INSANITY_PEN 1
 #define MINOR_INSANITY_PEN 5
 #define MAJOR_INSANITY_PEN 10
@@ -13,29 +14,39 @@
 	var/list/datum/mood_event/mood_events = list()
 	var/insanity_effect = 0 //is the owner being punished for low mood? If so, how much?
 	var/obj/screen/mood/screen_obj
+	var/datum/skill_modifier/bad_mood/malus
+	var/datum/skill_modifier/great_mood/bonus
+	var/static/malus_id = 0
+	var/static/bonus_id = 0
 
 /datum/component/mood/Initialize()
 	if(!isliving(parent))
 		return COMPONENT_INCOMPATIBLE
 
-	START_PROCESSING(SSmood, src)
+	var/mob/living/owner = parent
+	if(owner.stat != DEAD)
+		START_PROCESSING(SSdcs, src)
 
 	RegisterSignal(parent, COMSIG_ADD_MOOD_EVENT, .proc/add_event)
 	RegisterSignal(parent, COMSIG_CLEAR_MOOD_EVENT, .proc/clear_event)
 	RegisterSignal(parent, COMSIG_MODIFY_SANITY, .proc/modify_sanity)
 	RegisterSignal(parent, COMSIG_LIVING_REVIVE, .proc/on_revive)
 	RegisterSignal(parent, COMSIG_MOB_HUD_CREATED, .proc/modify_hud)
-	var/mob/living/owner = parent
+	RegisterSignal(parent, COMSIG_MOB_DEATH, .proc/stop_processing)
+
 	if(owner.hud_used)
 		modify_hud()
 		var/datum/hud/hud = owner.hud_used
 		hud.show_hud(hud.hud_version)
 
 /datum/component/mood/Destroy()
-	STOP_PROCESSING(SSmood, src)
+	STOP_PROCESSING(SSdcs, src)
 	unmodify_hud()
 	return ..()
 
+/datum/component/mood/proc/stop_processing()
+	STOP_PROCESSING(SSdcs, src)
+
 /datum/component/mood/proc/print_mood(mob/user)
 	var/msg = "<span class='info'>*---------*\n<EM>Your current mood</EM>\n"
 	msg += "<span class='notice'>My mental status: </span>" //Long term
@@ -127,7 +138,7 @@
 		else
 			screen_obj.icon_state = "mood[mood_level]"
 
-/datum/component/mood/process() //Called on SSmood process
+/datum/component/mood/process() //Called on SSdcs process
 	if(QDELETED(parent)) // workaround to an obnoxious sneaky periodical runtime.
 		qdel(src)
 		return
@@ -167,7 +178,6 @@
 	else if(sanity > maximum && amount > sanity - 0.5)
 		amount = sanity - 0.5
 
-	var/old_sanity = sanity
 	// Disturbed stops you from getting any more sane
 	if(HAS_TRAIT(master, TRAIT_UNSTABLE))
 		sanity = min(amount,sanity)
@@ -196,27 +206,41 @@
 			master.remove_movespeed_modifier(MOVESPEED_ID_SANITY)
 			sanity_level = 2
 		if(SANITY_GREAT+1 to INFINITY)
-			setInsanityEffect(0)
+			setInsanityEffect(ECSTATIC_SANITY_PEN) //It's not a penalty but w/e
 			master.remove_movespeed_modifier(MOVESPEED_ID_SANITY)
 			sanity_level = 1
 
-	if(old_sanity > 1 && sanity == 1)
-		RegisterSignal(master, COMSIG_MOB_SKILL_GET_AFFINITY, .proc/on_get_skill_affinity)
-	else if(old_sanity == 1 && sanity > 1)
-		UnregisterSignal(master, COMSIG_MOB_SKILL_GET_AFFINITY)
-
 	//update_mood_icon()
 
 /datum/component/mood/proc/setInsanityEffect(newval)//More code so that the previous proc works
 	if(newval == insanity_effect)
 		return
-	//var/mob/living/master = parent
-	//master.crit_threshold = (master.crit_threshold - insanity_effect) + newval
-	if(!insanity_effect && newval)
-		RegisterSignal(parent, COMSIG_MOB_ACTION_SKILL_MOD, .proc/on_mob_action_skill_mod)
-		RegisterSignal(parent, COMSIG_MOB_ITEM_ACTION_SKILLS_MOD, .proc/on_item_action_skills_mod)
-	else if(insanity_effect && !newval)
-		UnregisterSignal(parent, list(COMSIG_MOB_ACTION_SKILL_MOD, COMSIG_MOB_ITEM_ACTION_SKILLS_MOD))
+
+	var/mob/living/L = parent
+	var/apply_malus = newval >= SLIGHT_INSANITY_PEN
+	var/apply_bonus = !apply_malus && newval <= ECSTATIC_SANITY_PEN
+	if(apply_malus)
+		if(!malus)
+			malus = new(malus_id++)
+		var/debuff = 1 - (SANITY_DISTURBED - sanity) * MOOD_INSANITY_MALUS
+		malus.value_mod = malus.level_mod = debuff
+		if(!L.mind)
+			ADD_SKILL_MODIFIER_BODY(malus, L)
+		else
+			L.mind.add_skill_modifier(malus.identifier)
+	else if(malus)
+		QDEL_NULL(malus)
+
+	if(apply_bonus)
+		if(!bonus)
+			bonus = new(bonus_id++)
+		if(!L.mind)
+			ADD_SKILL_MODIFIER_BODY(bonus, L)
+		else
+			L.mind.add_skill_modifier(bonus.identifier)
+	else if(bonus)
+		QDEL_NULL(bonus)
+
 	insanity_effect = newval
 
 /datum/component/mood/proc/modify_sanity(datum/source, amount, minimum = SANITY_INSANE, maximum = SANITY_AMAZING)
@@ -294,46 +318,15 @@
 		if(0 to NUTRITION_LEVEL_STARVING)
 			add_event(null, "nutrition", /datum/mood_event/starving)
 
-///Called when parent is ahealed.
+///Called when parent is revived.
 /datum/component/mood/proc/on_revive(datum/source, full_heal)
+	START_PROCESSING(SSdcs, src)
 	if(!full_heal)
 		return
 	remove_temp_moods()
 	setSanity(initial(sanity))
 
-/datum/component/mood/proc/on_mob_action_skill_mod(mob/source, list/skill_args, list/mod_values)
-	var/datum/skill/S = GLOB.skill_datums[skill_args[ACTION_SKILL_MOD_SKILL]]
-	if(!(S.skill_flags & SKILL_USE_MOOD))
-		return
-	var/debuff = 1 - (SANITY_DISTURBED - sanity) * MOOD_INSANITY_MALUS
-	mod_values[MOD_VALUES_SKILL_MOD] *= skill_args[ACTION_SKILL_MOD_IS_MULTI] ? debuff : 1/debuff
-
-/datum/component/mood/proc/on_item_action_skills_mod(mob/source, list/skill_args, list/mod_values)
-	if(skill_args[ITEM_SKILLS_MOD_BAD_FLAGS] & SKILL_USE_MOOD)
-		return
-	var/divisor = mod_values[MOD_VALUES_ITEM_SKILLS_DIV]
-	if(!divisor)
-		return
-	var/obj/item/I = skill_args[ITEM_SKILLS_MOD_ITEM]
-	var/list/L = mod_values[MOD_VALUES_ITEM_SKILLS_CHECKED]
-	var/skills_len = length(L)
-	var/affected_skills = skills_len
-	for(var/k in L)
-		var/datum/skill/S = k
-		var/our_flags = I.used_skills[S.type]|S.skill_flags
-		if(!(our_flags & SKILL_USE_MOOD))
-			affected_skills--
-	if(!affected_skills)
-		return
-	var/debuff = 1 - (SANITY_DISTURBED - sanity) * MOOD_INSANITY_MALUS * (affected_skills/skills_len)
-	mod_values[MOD_VALUES_ITEM_SKILLS_SUM] *= skill_args[ITEM_SKILLS_MOD_IS_MULTI] ? debuff : 1/debuff
-
-/datum/component/mood/proc/on_get_skill_affinity(mob/source, skill_path, list/return_value)
-	var/datum/skill/S = GLOB.skill_datums[skill_path]
-	if(!S || !(S.skill_flags & SKILL_TRAIN_MOOD))
-		return
-	return_value[1] *= SKILL_AFFINITY_MOOD_BONUS
-
+#undef ECSTATIC_SANITY_PEN
 #undef SLIGHT_INSANITY_PEN
 #undef MINOR_INSANITY_PEN
 #undef MAJOR_INSANITY_PEN
diff --git a/code/datums/mind.dm b/code/datums/mind.dm
index 54fcbbc6aa..ee8762e9da 100644
--- a/code/datums/mind.dm
+++ b/code/datums/mind.dm
@@ -67,7 +67,7 @@
 	var/datum/skill_holder/skill_holder
 
 /datum/mind/New(var/key)
-	skill_holder = new(src)
+	skill_holder = new()
 	src.key = key
 	soulOwner = src
 	martial_art = default_martial_art
diff --git a/code/datums/skills/_check_skills.dm b/code/datums/skills/_check_skills.dm
index d9dc6dad3d..a94c7c95ba 100644
--- a/code/datums/skills/_check_skills.dm
+++ b/code/datums/skills/_check_skills.dm
@@ -12,5 +12,5 @@
 		to_chat(usr, "<span class='warning'>How do you check the skills of [(usr == src)? "yourself when you are" : "something"] without the capability for skills? (PROBABLY A BUG, PRESS F1.)</span>")
 		return
 	var/datum/browser/B = new(usr, "skilldisplay_[REF(src)]", "Skills of [src]")
-	B.set_content(mind.skill_holder.html_readout())
+	B.set_content(mind.skill_html_readout())
 	B.open()
diff --git a/code/datums/skills/_skill.dm b/code/datums/skills/_skill.dm
index f52945536f..04ed7bdc59 100644
--- a/code/datums/skills/_skill.dm
+++ b/code/datums/skills/_skill.dm
@@ -9,19 +9,10 @@ GLOBAL_LIST_INIT_TYPED(skill_datums, /datum/skill, init_skill_datums())
 		S = new path
 		.[S.type] = S
 
-/proc/sanitize_skill_value(path, value)
-	var/datum/skill/S = GLOB.skill_datums[path]
-	// don't check, if we runtime let it happen.
-	return S.sanitize_value(value)
-
-/proc/is_skill_value_greater(path, existing, new_value)
-	var/datum/skill/S = GLOB.skill_datums[path]
-	// don't check, if we runtime let it happen.
-	return S.is_value_greater(existing, new_value)
-
 /**
   * Skill datums
   */
+
 /datum/skill
 	/// Our name
 	var/name
@@ -33,11 +24,13 @@ GLOBAL_LIST_INIT_TYPED(skill_datums, /datum/skill, init_skill_datums())
 	var/progression_type
 	/// Abstract type
 	var/abstract_type = /datum/skill
-	/// skill threshold used in generic skill modifiers calculations.
+	/// List of max levels. Only used in level skills, but present here for helper macros.
+	var/max_levels = INFINITY
+	/// skill threshold used in generic skill competency calculations.
 	var/list/competency_thresholds = list(0, 0, 0)
 	/// Multiplier of the difference of the holder skill value and the selected threshold.
 	var/list/competency_mults = list(0, 0, 0)
-	/// In which way this skil can affect or be affected through actions.
+	/// In which way this skil can affect or be affected through actions and skill modifiers.
 	var/skill_flags = SKILL_USE_MOOD|SKILL_TRAIN_MOOD
 
 /**
@@ -114,9 +107,9 @@ GLOBAL_LIST_INIT_TYPED(skill_datums, /datum/skill, init_skill_datums())
 /datum/skill/level
 	abstract_type = /datum/skill/level
 	progression_type = SKILL_PROGRESSION_LEVEL
+	max_levels = STD_MAX_LVL
 	var/standard_xp_lvl_up = STD_XP_LVL_UP //the standard required to level up. def: 100
 	var/xp_lvl_multiplier = STD_XP_LVL_MULTI //standard required level up exp multiplier. def: 2 (100, 200, 400, 800 etc.)
-	var/max_levels = STD_MAX_LVL
 	var/level_up_method = STANDARD_LEVEL_UP //how levels are calculated.
 	var/list/levels = list() //level thresholds, if associative, these will be preceded by tiers such as "novice" or "trained"
 	var/associative = FALSE //See above.
@@ -182,7 +175,6 @@ GLOBAL_LIST_INIT_TYPED(skill_datums, /datum/skill, init_skill_datums())
 	if(next_lvl_xp > current_lvl_xp_sum)
 		next_lvl_xp -= current_lvl_xp_sum
 
-
 	return "[associative ? current_lvl : "Lvl. [current_lvl]"] ([value - current_lvl_xp_sum]/[next_lvl_xp])[level == max_levels ? " \[MAX!\]" : ""]"
 
 /datum/skill/level/job
diff --git a/code/datums/skills/_skill_holder.dm b/code/datums/skills/_skill_holder.dm
index e252b4c9c6..0ce2c2b9db 100644
--- a/code/datums/skills/_skill_holder.dm
+++ b/code/datums/skills/_skill_holder.dm
@@ -1,8 +1,8 @@
 /**
   * Skill holder datums
+  * All procs are tied to the mind, since they are always expected to have a skill holder anyway.
   */
 /datum/skill_holder
-	var/datum/mind/owner
 	/// Our list of skills and values. Lazylist. Associative. Keys are datum typepaths to the skill.
 	var/list/skills
 	/// Same as [skills] but affinities, which are multiplied to increase amount when gaining skills.
@@ -10,66 +10,87 @@
 	/// Let's say we want to get a specific skill "level" without looping through a proc everytime.
 	/// Only supported by skills with tiers or levels.
 	var/list/skill_levels
-
-/datum/skill_holder/New(datum/mind/M)
-	. = ..()
-	owner = M
+	/// current skill modifiers lists, per value, affinity, level.
+	var/list/skill_value_mods
+	var/list/skill_affinity_mods
+	var/list/skill_level_mods
+	/// List of all current skill modifiers, so we don't add the same ones twice.
+	var/list/all_current_skill_modifiers
+	/// List of original values stored at the time a modifier with the MODIFIER_SKILL_ORIGIN_DIFF enabled was added.
+	var/list/original_values
+	var/list/original_affinities
+	var/list/original_levels
 
 /**
   * Grabs the value of a skill.
   */
-/datum/skill_holder/proc/get_skill_value(skill)
+/datum/mind/proc/get_skill_value(skill, apply_modifiers = TRUE)
 	if(!ispath(skill))
 		CRASH("Invalid get_skill_value call. Use typepaths.")		//until a time when we somehow need text ids for dynamic skills, I'm enforcing this.
-	if(!skills)
+	if(!(skill_holder?.skills))
 		return null
-	return skills[skill]
+	else
+		. = skill_holder.skills[skill]
+	if(apply_modifiers && skill_holder.skill_value_mods)
+		var/L = LAZYACCESS(skill_holder.skill_value_mods, skill)
+		for(var/k in L)
+			var/datum/skill_modifier/M = GLOB.skill_modifiers[k]
+			. = M.apply_modifier(., skill, skill_holder, MODIFIER_TARGET_VALUE)
 
 /**
   * Grabs the level of a skill. Only supported by skills with tiers or levels.
   */
-/datum/skill_holder/proc/get_skill_level(skill)
+/datum/mind/proc/get_skill_level(skill, apply_modifiers = TRUE, round = FALSE)
 	if(!ispath(skill, /datum/skill))
 		CRASH("Invalid get_skill_value call. Use skill typepaths.")	//until a time when we somehow need text ids for dynamic skills, I'm enforcing this.
-	if(!skill_levels)
-		return 0
-	return skill_levels[skill]
+	if(!skill_holder.skill_levels)
+		. =  0
+	else
+		. = skill_holder.skill_levels[skill] || 0
+	if(apply_modifiers && skill_holder.skill_level_mods)
+		var/L = LAZYACCESS(skill_holder.skill_level_mods, skill)
+		for(var/k in L)
+			var/datum/skill_modifier/M = GLOB.skill_modifiers[k]
+			. = M.apply_modifier(., skill, skill_holder, MODIFIER_TARGET_LEVEL)
+		. = SANITIZE_SKILL_LEVEL(skill, round ? round(.) : .)
 
 /**
   * Grabs our affinity for a skill. !!This is a multiplier!!
   */
-/datum/skill_holder/proc/get_skill_affinity(skill)
+/datum/mind/proc/get_skill_affinity(skill, apply_modifiers = TRUE)
 	. = 1
 	if(!ispath(skill, /datum/skill))
 		CRASH("Invalid get_skill_affinity call. Use skill typepaths.")	//until a time when we somehow need text ids for dynamic skills, I'm enforcing this.
-	var/affinity = LAZYACCESS(skill_affinities, skill)
+	var/affinity = LAZYACCESS(skill_holder.skill_affinities, skill)
 	if(!isnull(affinity))
 		. = affinity
-	var/list/wrapped = list(.)
-	SEND_SIGNAL(owner.current, COMSIG_MOB_SKILL_GET_AFFINITY, skill, wrapped)
-	. = wrapped[1]
+	if(apply_modifiers && skill_holder.skill_affinity_mods)
+		var/L = LAZYACCESS(skill_holder.skill_affinity_mods, skill)
+		for(var/k in L)
+			var/datum/skill_modifier/M = GLOB.skill_modifiers[k]
+			. = M.apply_modifier(., skill, skill_holder, MODIFIER_TARGET_AFFINITY)
 
 
 /**
   * Sets the value of a skill.
   */
-/datum/skill_holder/proc/set_skill_value(skill, value, silent = FALSE)
+/datum/mind/proc/set_skill_value(skill, value, silent = FALSE)
 	if(!ispath(skill, /datum/skill))
 		CRASH("Invalid set_skill_value call. Use skill typepaths.")	//until a time when we somehow need text ids for dynamic skills, I'm enforcing this.
 	var/datum/skill/S = GLOB.skill_datums[skill]
 	value = S.sanitize_value(value)
 	if(!isnull(value))
-		LAZYINITLIST(skills)
-		S.set_skill_value(src, value, owner, silent)
+		LAZYINITLIST(skill_holder.skills)
+		S.set_skill_value(skill_holder, value, src, silent)
 		return TRUE
 	return FALSE
 
 /**
   * Boosts a skill to a value if not aobve
   */
-/datum/skill_holder/proc/boost_skill_value_to(skill, value, silent = FALSE)
-	var/current = get_skill_value(skill)
-	if(!is_skill_value_greater(skill, current, value))
+/datum/mind/proc/boost_skill_value_to(skill, value, silent = FALSE, current)
+	current = current || get_skill_value(skill, FALSE)
+	if(!IS_SKILL_VALUE_GREATER(skill, current, value))
 		return FALSE
 	set_skill_value(skill, value, silent)
 	return TRUE
@@ -78,20 +99,20 @@
   * Automatic skill increase, multiplied by skill affinity if existing.
   * Only works if skill is numerical.
   */
-/datum/skill_holder/proc/auto_gain_experience(skill, value, maximum, silent = FALSE)
+/datum/mind/proc/auto_gain_experience(skill, value, maximum, silent = FALSE)
 	if(!ispath(skill, /datum/skill))
 		CRASH("Invalid set_skill_value call. Use skill typepaths.")
 	var/datum/skill/S = GLOB.skill_datums[skill]
 	if(S.progression_type != SKILL_PROGRESSION_NUMERICAL && S.progression_type != SKILL_PROGRESSION_LEVEL)
 		CRASH("You cannot auto increment a non numerical(experience skill!")
-	var/current = get_skill_value(skill)
+	var/current = get_skill_value(skill, FALSE)
 	var/affinity = get_skill_affinity(skill)
 	var/target_value = current + (value * affinity)
 	if(maximum)
 		target_value = max(target_value, maximum)
 		if(target_value == maximum) //no more experience to gain, early return.
 			return
-	boost_skill_value_to(skill, target_value, silent)
+	boost_skill_value_to(skill, target_value, silent, current)
 
 /**
   * Generic value modifier proc that uses one skill.
@@ -100,22 +121,17 @@
   * * threshold : The difficulty of the action, in short. Refer to __DEFINES/skills/defines.dm for the defines.
   * * modifier_is_multiplier : wheter the modifier is a multiplier or a divisor.
   */
-/datum/skill_holder/proc/action_skills_mod(skill, value, threshold, modifier_is_multiplier = TRUE)
+/datum/mind/proc/action_skill_mod(skill, value, threshold, modifier_is_multiplier = TRUE)
 	var/mod
 	var/datum/skill/S = GLOB.skill_datums[skill]
 	if(!S)
 		return
 	switch(S.progression_type)
 		if(SKILL_PROGRESSION_LEVEL)
-			mod = LAZYACCESS(skill_levels, S.type)
+			mod = get_skill_level(S.type)
 		else
-			mod = LAZYACCESS(skills, S.type)
+			mod = get_skill_value(S.type)
 	mod = (1+(mod-S.competency_thresholds[threshold])*S.competency_mults[threshold])
-
-	var/list/comsig_values = list(mod)
-	SEND_SIGNAL(owner.current, COMSIG_MOB_ACTION_SKILL_MOD, args, comsig_values)
-	mod = comsig_values[MOD_VALUES_SKILL_MOD]
-
 	. = modifier_is_multiplier ? value*mod : value/mod
 
 /**
@@ -128,11 +144,10 @@
   * * bad_flags : the opposite of the above, skills that must not be present to impact the value.
   * * modifier_is_multiplier : wheter the modifier is a multiplier or a divisor.
   */
-/datum/skill_holder/proc/item_action_skills_mod(obj/item/I, value, flags = NONE, bad_flags = NONE, modifier_is_multiplier = TRUE)
+/datum/mind/proc/item_action_skills_mod(obj/item/I, value, flags = NONE, bad_flags = NONE, modifier_is_multiplier = TRUE)
 	. = value
 	var/sum = 0
 	var/divisor = 0
-	var/list/checked_skills
 	for(var/k in I.used_skills)
 		var/datum/skill/S = GLOB.skill_datums[k]
 		if(!S)
@@ -143,17 +158,10 @@
 		var/mod
 		switch(S.progression_type)
 			if(SKILL_PROGRESSION_LEVEL)
-				mod = LAZYACCESS(skill_levels, S.type)
+				mod = get_skill_level(S.type)
 			else
-				mod = LAZYACCESS(skills, S.type)
+				mod = get_skill_value(S.type)
 		sum += 1+(mod - S.competency_thresholds[I.skill_difficulty])*S.competency_mults[I.skill_difficulty]
-		LAZYADD(checked_skills, S)
-
-	var/list/comsig_values = list(sum, divisor, checked_skills)
-	SEND_SIGNAL(owner.current, COMSIG_MOB_ITEM_ACTION_SKILLS_MOD, args, comsig_values)
-	sum = comsig_values[MOD_VALUES_ITEM_SKILLS_SUM]
-	divisor = comsig_values[MOD_VALUES_ITEM_SKILLS_DIV]
-
 	if(divisor)
 		. = modifier_is_multiplier ? value*(sum/divisor) : value/(sum/divisor)
 
@@ -161,11 +169,13 @@
   * Generates a HTML readout of our skills.
   * Port to tgui-next when?
   */
-/datum/skill_holder/proc/html_readout()
+/datum/mind/proc/skill_html_readout()
 	var/list/out = list("<center><h1>Skills</h1></center><hr>")
 	out += "<table style=\"width:100%\"><tr><th><b>Skill</b><th><b>Value</b></tr>"
-	for(var/path in skills)
+	for(var/path in skill_holder.skills)
 		var/datum/skill/S = GLOB.skill_datums[path]
-		out += "<tr><td><font color='[S.name_color]'>[S.name]</font></td><td>[S.standard_render_value(skills[path], LAZYACCESS(skill_levels, path) || 0)]</td></tr>"
+		var/skill_value = get_skill_value(path)
+		var/skill_level = get_skill_level(path, round = TRUE)
+		out += "<tr><td><font color='[S.name_color]'>[S.name]</font></td><td>[S.standard_render_value(skill_value, skill_level)]</td></tr>"
 	out += "</table>"
 	return out.Join("")
diff --git a/code/datums/skills/_skill_modifier.dm b/code/datums/skills/_skill_modifier.dm
new file mode 100644
index 0000000000..b6ad27c070
--- /dev/null
+++ b/code/datums/skills/_skill_modifier.dm
@@ -0,0 +1,176 @@
+GLOBAL_LIST_EMPTY_TYPED(skill_modifiers, /datum/skill_modifier)
+GLOBAL_LIST_EMPTY(potential_skills_per_mod)
+GLOBAL_LIST_EMPTY(potential_mods_per_skill)
+
+/**
+  * Base skill modifier datum, used to modify a player skills without directly touching their values, levels and affinity
+  * and cause lots of edge cases. These are fairly simple overall... make a subtype though, don't use this one.
+  */
+/datum/skill_modifier
+	/// flags for this skill modifier.
+	var/modifier_flags = NONE
+	/// target skills, can be a specific skill typepath or a set of skill flags.
+	var/target_skills = ALL
+	/// The identifier key this skill modifier is associated with.
+	var/identifier
+	/// skill affinity modifier, can be a multiplier or addendum, depending on the modifier_flags flags.
+	var/affinity_mod = 1
+	/// skill value modifier, see above.
+	var/value_mod = 1
+	/// skill level modifier, see above.
+	var/level_mod = 1
+	/// Priority of this skill modifier compared to other ones.
+	var/priority = MODIFIER_SKILL_PRIORITY_DEF
+
+/datum/skill_modifier/New(id)
+	identifier = type
+	if(id)
+		identifier = "[type]&[id]"
+		var/dupe = 0
+		while(GLOB.skill_modifiers[identifier])
+			identifier = "[type]&[id][++dupe]"
+	GLOB.skill_modifiers[identifier] = src
+
+	if(ispath(target_skills))
+		var/list/mod_L = GLOB.potential_mods_per_skill[target_skills]
+		if(!mod_L)
+			GLOB.potential_mods_per_skill[target_skills] = list(identifier = src)
+		else
+			BINARY_INSERT(identifier, mod_L, datum/skill_modifier, src, priority, COMPARE_VALUE)
+			mod_L[identifier] = src
+		GLOB.potential_skills_per_mod["[target_skills]"] = list(target_skills)
+	else //Should be a bitfield.
+		var/list/L = GLOB.potential_skills_per_mod["[target_skills]"]
+		if(!L)
+			L = list()
+			for(var/path in GLOB.skill_datums)
+				if(GLOB.skill_datums[path].skill_flags & target_skills)
+					L += path
+			GLOB.potential_skills_per_mod["[target_skills]"] = L
+		for(var/path in L)
+			var/list/mod_L = GLOB.potential_mods_per_skill[path]
+			if(!mod_L)
+				GLOB.potential_mods_per_skill[path] = list(identifier = src)
+			else
+				BINARY_INSERT(identifier, mod_L, datum/skill_modifier, src, priority, COMPARE_VALUE)
+				mod_L[identifier] = src
+
+/datum/skill_modifier/Destroy()
+	for(var/A in GLOB.potential_skills_per_mod["[target_skills]"])
+		LAZYREMOVEASSOC(GLOB.potential_mods_per_skill, A, identifier)
+	GLOB.potential_skills_per_mod -= "[target_skills]"
+	GLOB.skill_modifiers -= src
+	return ..()
+
+#define ADD_MOD_STEP(L, P, O, G) \
+	var/__L = L[P];\
+	if(!__L){\
+		L[P] = list(id)\
+	} else {\
+		L[P] = GLOB.potential_mods_per_skill[P] & (__L + id)\
+	}\
+	if(M.modifier_flags & MODIFIER_SKILL_ORIGIN_DIFF){\
+		LAZYADDASSOC(O, id, P = G)\
+	}
+
+/datum/mind/proc/add_skill_modifier(id)
+	if(skill_holder.all_current_skill_modifiers[id])
+		return
+	var/datum/skill_modifier/M = GLOB.skill_modifiers[id]
+	if(!M)
+		CRASH("Invalid add_skill_modifier id: [id].")
+	if(M.modifier_flags & MODIFIER_SKILL_BODYBOUND && !current)
+		CRASH("Body-bound skill modifier [M] was tried to be added to a mob-less mind.")
+
+	if(M.modifier_flags & MODIFIER_SKILL_VALUE)
+		LAZYINITLIST(skill_holder.skill_value_mods)
+	if(M.modifier_flags & MODIFIER_SKILL_AFFINITY)
+		LAZYINITLIST(skill_holder.skill_affinity_mods)
+	if(M.modifier_flags & MODIFIER_SKILL_LEVEL)
+		LAZYINITLIST(skill_holder.skill_level_mods)
+	for(var/path in GLOB.potential_skills_per_mod["[M.target_skills]"])
+		if(M.modifier_flags & MODIFIER_SKILL_VALUE)
+			ADD_MOD_STEP(skill_holder.skill_value_mods, path, skill_holder.original_values, get_skill_value(path, FALSE))
+		if(M.modifier_flags & MODIFIER_SKILL_AFFINITY)
+			ADD_MOD_STEP(skill_holder.skill_affinity_mods, path, skill_holder.original_affinities, get_skill_affinity(path, FALSE))
+		if(M.modifier_flags & MODIFIER_SKILL_LEVEL)
+			ADD_MOD_STEP(skill_holder.skill_level_mods, path, skill_holder.original_levels, get_skill_level(path, FALSE))
+	LAZYSET(skill_holder.all_current_skill_modifiers, id, TRUE)
+
+	if(M.modifier_flags & MODIFIER_SKILL_BODYBOUND)
+		M.RegisterSignal(src, COMSIG_MIND_TRANSFER, /datum/skill_modifier.proc/on_mind_transfer)
+		ADD_SKILL_MODIFIER_BODY(M, current)
+	RegisterSignal(M, COMSIG_PARENT_QDELETING, .proc/on_skill_modifier_deletion)
+
+#undef ADD_MOD_STEP
+
+#define REMOVE_MOD_STEP(L, P, O)\
+	LAZYREMOVEASSOC(L, P, id);\
+	if(M.modifier_flags & MODIFIER_SKILL_ORIGIN_DIFF){\
+		LAZYREMOVEASSOC(O, id, P)\
+	}
+
+/datum/mind/proc/remove_skill_modifier(id, mind_transfer = FALSE)
+	if(!LAZYACCESS(skill_holder.all_current_skill_modifiers, id))
+		return
+	var/datum/skill_modifier/M = GLOB.skill_modifiers[id]
+	if(!M)
+		CRASH("Invalid remove_skill_modifier id: [id].")
+
+	if(!skill_holder.skill_value_mods && !skill_holder.skill_affinity_mods && !skill_holder.skill_level_mods)
+		return
+	for(var/path in GLOB.potential_skills_per_mod["[M.target_skills]"])
+		if(M.modifier_flags & MODIFIER_SKILL_VALUE && skill_holder.skill_value_mods)
+			REMOVE_MOD_STEP(skill_holder.skill_value_mods, path, skill_holder.original_values)
+		if(M.modifier_flags & MODIFIER_SKILL_AFFINITY)
+			REMOVE_MOD_STEP(skill_holder.skill_affinity_mods, path, skill_holder.original_affinities)
+		if(M.modifier_flags & MODIFIER_SKILL_LEVEL)
+			REMOVE_MOD_STEP(skill_holder.skill_level_mods, path, skill_holder.original_levels)
+	LAZYREMOVE(skill_holder.all_current_skill_modifiers, id)
+
+	if(!mind_transfer && M.modifier_flags & MODIFIER_SKILL_BODYBOUND)
+		M.UnregisterSignal(src, COMSIG_MIND_TRANSFER)
+		M.UnregisterSignal(current, list(COMSIG_MOB_ON_NEW_MIND))
+	UnregisterSignal(M, COMSIG_PARENT_QDELETING)
+
+#undef REMOVE_MOD_STEP
+
+/datum/mind/proc/on_skill_modifier_deletion(datum/skill_modifier/source)
+	remove_skill_modifier(source.identifier)
+
+/datum/skill_modifier/proc/apply_modifier(value, skillpath, datum/skill_holder/H, method = MODIFIER_TARGET_VALUE)
+	. = value
+	var/mod = value_mod
+	switch(method)
+		if(MODIFIER_TARGET_LEVEL)
+			mod = level_mod
+		if(MODIFIER_TARGET_AFFINITY)
+			mod = affinity_mod
+
+	if(modifier_flags & (MODIFIER_SKILL_VIRTUE|MODIFIER_SKILL_HANDICAP))
+		if(modifier_flags & MODIFIER_SKILL_VIRTUE)
+			. = max(., mod)
+		if(modifier_flags & MODIFIER_SKILL_HANDICAP)
+			. = min(., mod)
+	else if(modifier_flags & MODIFIER_SKILL_MULT)
+		. *= mod
+	else
+		. += mod
+
+	if(modifier_flags & MODIFIER_SKILL_ORIGIN_DIFF)
+		var/list/to_access = H.original_values
+		switch(method)
+			if(MODIFIER_TARGET_LEVEL)
+				to_access = H.original_levels
+			if(MODIFIER_TARGET_AFFINITY)
+				to_access = H.original_affinities
+		. += value - LAZYACCESS(to_access[identifier], skillpath)
+
+///Body bound modifier signal procs.
+/datum/skill_modifier/proc/on_mind_transfer(datum/mind/source, mob/new_character, mob/old_character)
+	source.remove_skill_modifier(identifier, TRUE)
+	UnregisterSignal(source, COMSIG_MIND_TRANSFER)
+
+/datum/skill_modifier/proc/on_mob_new_mind(mob/source)
+	source.mind.add_skill_modifier(identifier)
+	RegisterSignal(source.mind, COMSIG_MIND_TRANSFER, /datum/skill_modifier.proc/on_mind_transfer)
diff --git a/code/datums/skills/modifiers/job.dm b/code/datums/skills/modifiers/job.dm
new file mode 100644
index 0000000000..45475fb9db
--- /dev/null
+++ b/code/datums/skills/modifiers/job.dm
@@ -0,0 +1,34 @@
+/// Jobbie level skill modifiers.
+
+/datum/skill_modifier/job
+	modifier_flags = MODIFIER_SKILL_VALUE|MODIFIER_SKILL_LEVEL|MODIFIER_SKILL_VIRTUE|MODIFIER_SKILL_ORIGIN_DIFF
+	priority = MODIFIER_SKILL_PRIORITY_MAX
+
+/datum/skill_modifier/job
+	level_mod = JOB_SKILL_TRAINED
+
+/datum/skill_modifier/job/surgery
+	target_skills = /datum/skill/numerical/surgery
+	value_mod = STARTING_SKILL_SURGERY_MEDICAL
+
+/datum/skill_modifier/job/affinity
+	modifier_flags = MODIFIER_SKILL_AFFINITY|MODIFIER_SKILL_VIRTUE
+	affinity_mod = STARTING_SKILL_AFFINITY_DEF_JOB
+
+/datum/skill_modifier/job/affinity/surgery
+	target_skills = /datum/skill/numerical/surgery
+
+/datum/skill_modifier/job/affinity/wiring
+	target_skills = /datum/skill/level/job/wiring
+
+/// Level skill modifiers below.
+/datum/skill_modifier/job/level/New(id)
+	if(level_mod)
+		value_mod = GET_STANDARD_LVL(level_mod)
+	..()
+
+/datum/skill_modifier/job/level/wiring
+	target_skills = /datum/skill/level/job/wiring
+
+/datum/skill_modifier/job/level/wiring/basic
+	level_mod = JOB_SKILL_BASIC
diff --git a/code/datums/skills/modifiers/mood.dm b/code/datums/skills/modifiers/mood.dm
new file mode 100644
index 0000000000..2ab74bdbbb
--- /dev/null
+++ b/code/datums/skills/modifiers/mood.dm
@@ -0,0 +1,8 @@
+/datum/skill_modifier/bad_mood
+	modifier_flags = MODIFIER_SKILL_VALUE|MODIFIER_SKILL_LEVEL|MODIFIER_SKILL_MULT|MODIFIER_SKILL_BODYBOUND
+	target_skills = SKILL_USE_MOOD
+
+/datum/skill_modifier/great_mood
+	modifier_flags = MODIFIER_SKILL_AFFINITY|MODIFIER_SKILL_MULT|MODIFIER_SKILL_BODYBOUND
+	target_skills = SKILL_TRAIN_MOOD
+	affinity_mod = 1.2
diff --git a/code/datums/wires/_wires.dm b/code/datums/wires/_wires.dm
index d2f719c50c..e020afa47a 100644
--- a/code/datums/wires/_wires.dm
+++ b/code/datums/wires/_wires.dm
@@ -138,7 +138,7 @@
 	if(current_users[user])
 		return FALSE
 	if(req_skill && user?.mind)
-		var/level_diff = req_skill - user.mind.skill_holder.get_skill_level(/datum/skill/level/job/wiring)
+		var/level_diff = req_skill - user.mind.get_skill_level(/datum/skill/level/job/wiring)
 		if(level_diff > 0)
 			LAZYSET(current_users, user, TRUE)
 			to_chat(user, "<span class='notice'>You begin cutting [holder]'s [color] wire...</span>")
@@ -167,7 +167,7 @@
 	if(current_users[user])
 		return FALSE
 	if(req_skill && user?.mind)
-		var/level_diff = req_skill - user.mind.skill_holder.get_skill_level(/datum/skill/level/job/wiring)
+		var/level_diff = req_skill - user.mind.get_skill_level(/datum/skill/level/job/wiring)
 		if(level_diff > 0)
 			LAZYSET(current_users, user, TRUE)
 			to_chat(user, "<span class='notice'>You begin pulsing [holder]'s [color] wire...</span>")
@@ -255,7 +255,7 @@
 	var/reveal_wires = FALSE
 
 	// Admin ghost can see a purpose of each wire.
-	if(IsAdminGhost(user) || user.mind.skill_holder.get_skill_level(/datum/skill/level/job/wiring) >= req_knowledge)
+	if(IsAdminGhost(user) || user.mind.get_skill_level(/datum/skill/level/job/wiring) >= req_knowledge)
 		reveal_wires = TRUE
 
 	// Same for anyone with an abductor multitool.
diff --git a/code/game/objects/items.dm b/code/game/objects/items.dm
index 949ed050f5..dde56e8278 100644
--- a/code/game/objects/items.dm
+++ b/code/game/objects/items.dm
@@ -802,7 +802,7 @@ GLOBAL_VAR_INIT(rpg_loot_items, FALSE)
 
 	if(delay)
 		if(user.mind && used_skills)
-			delay = user.mind.skill_holder.item_action_skills_mod(src, delay, skill_difficulty, SKILL_USE_TOOL, NONE, FALSE)
+			delay = user.mind.item_action_skills_mod(src, delay, skill_difficulty, SKILL_USE_TOOL, NONE, FALSE)
 
 		// Create a callback with checks that would be called every tick by do_after.
 		var/datum/callback/tool_check = CALLBACK(src, .proc/tool_check_callback, user, amount, extra_checks)
@@ -832,7 +832,7 @@ GLOBAL_VAR_INIT(rpg_loot_items, FALSE)
 		for(var/skill in used_skills)
 			if(!(used_skills[skill] & SKILL_TRAINING_TOOL))
 				continue
-			user.mind.skill_holder.auto_gain_experience(skill, skill_gain*skill_gain_mult, GET_STANDARD_LVL(max_level))
+			user.mind.auto_gain_experience(skill, skill_gain*skill_gain_mult, GET_STANDARD_LVL(max_level))
 
 	return TRUE
 
diff --git a/code/modules/admin/verbs/SDQL2/SDQL_2.dm b/code/modules/admin/verbs/SDQL2/SDQL_2.dm
index 26736ddff1..df54df5c7d 100644
--- a/code/modules/admin/verbs/SDQL2/SDQL_2.dm
+++ b/code/modules/admin/verbs/SDQL2/SDQL_2.dm
@@ -1025,8 +1025,6 @@ GLOBAL_DATUM_INIT(sdql2_vv_statobj, /obj/effect/statclick/SDQL2_VV_all, new(null
 				v = SSnpcpool
 			if("SSmobs")
 				v = SSmobs
-			if("SSmood")
-				v = SSmood
 			if("SSquirks")
 				v = SSquirks
 			if("SSwet_floors")
diff --git a/code/modules/jobs/job_types/_job.dm b/code/modules/jobs/job_types/_job.dm
index e10f009cec..426e5136c9 100644
--- a/code/modules/jobs/job_types/_job.dm
+++ b/code/modules/jobs/job_types/_job.dm
@@ -66,10 +66,8 @@
 	// How much threat this job is worth in dynamic. Is subtracted if the player's not an antag, added if they are.
 	var/threat = 0
 
-	/// Starting skill levels.
-	var/list/starting_skills
-	/// Skill affinities to set
-	var/list/skill_affinities
+	/// Starting skill modifiers.
+	var/list/starting_modifiers
 
 //Only override this proc
 //H is usually a human unless an /equip override transformed it
@@ -171,15 +169,10 @@
 	to_chat(M, "<b>Prefix your message with :h to speak on your department's radio. To see other prefixes, look closely at your headset.</b>")
 
 /datum/job/proc/standard_assign_skills(datum/mind/M)
-	if(!starting_skills)
+	if(!starting_modifiers)
 		return
-	for(var/skill in starting_skills)
-		M.skill_holder.boost_skill_value_to(skill, starting_skills[skill], TRUE) //silent
-	// do wipe affinities though
-	M.skill_holder.skill_affinities = list()
-	for(var/skill in skill_affinities)
-		M.skill_holder.skill_affinities[skill] = skill_affinities[skill]
-	UNSETEMPTY(M.skill_holder.skill_affinities)		//if we didn't set any.
+	for(var/mod in starting_modifiers)
+		ADD_SINGLETON_SKILL_MODIFIER(M, mod, null)
 
 /datum/outfit/job
 	name = "Standard Gear"
diff --git a/code/modules/jobs/job_types/ai.dm b/code/modules/jobs/job_types/ai.dm
index 1395b90b39..a7401791ab 100644
--- a/code/modules/jobs/job_types/ai.dm
+++ b/code/modules/jobs/job_types/ai.dm
@@ -17,7 +17,7 @@
 	var/do_special_check = TRUE
 	threat = 5
 
-	starting_skills = list(/datum/skill/level/job/wiring = GET_STANDARD_LVL(JOB_SKILL_BASIC))
+	starting_modifiers = list(/datum/skill_modifier/job/level/wiring/basic)
 
 /datum/job/ai/equip(mob/living/carbon/human/H, visualsOnly, announce, latejoin, datum/outfit/outfit_override, client/preference_source = null)
 	if(visualsOnly)
diff --git a/code/modules/jobs/job_types/atmospheric_technician.dm b/code/modules/jobs/job_types/atmospheric_technician.dm
index 42c6afaed8..fc104809c3 100644
--- a/code/modules/jobs/job_types/atmospheric_technician.dm
+++ b/code/modules/jobs/job_types/atmospheric_technician.dm
@@ -18,8 +18,7 @@
 	minimal_access = list(ACCESS_ATMOSPHERICS, ACCESS_MAINT_TUNNELS, ACCESS_EXTERNAL_AIRLOCKS, ACCESS_ENGINE,
 									ACCESS_ENGINE_EQUIP, ACCESS_EMERGENCY_STORAGE, ACCESS_CONSTRUCTION, ACCESS_MINERAL_STOREROOM)
 
-	starting_skills = list(/datum/skill/level/job/wiring = GET_STANDARD_LVL(JOB_SKILL_BASIC))
-	skill_affinities = list(/datum/skill/level/job/wiring = STARTING_SKILL_AFFINITY_WIRING_ENGI_ROBO)
+	starting_modifiers = list(/datum/skill_modifier/job/level/wiring/basic, /datum/skill_modifier/job/affinity/wiring)
 
 	display_order = JOB_DISPLAY_ORDER_ATMOSPHERIC_TECHNICIAN
 	threat = 0.5
diff --git a/code/modules/jobs/job_types/chemist.dm b/code/modules/jobs/job_types/chemist.dm
index 571785526b..f3144ff027 100644
--- a/code/modules/jobs/job_types/chemist.dm
+++ b/code/modules/jobs/job_types/chemist.dm
@@ -19,8 +19,7 @@
 	display_order = JOB_DISPLAY_ORDER_CHEMIST
 	threat = 1.5
 
-	starting_skills = list(/datum/skill/numerical/surgery = STARTING_SKILL_SURGERY_MEDICAL)
-	skill_affinities = list(/datum/skill/numerical/surgery = STARTING_SKILL_AFFINITY_SURGERY_MEDICAL)
+	starting_modifiers = list(/datum/skill_modifier/job/surgery, /datum/skill_modifier/job/affinity/surgery)
 
 /datum/outfit/job/chemist
 	name = "Chemist"
diff --git a/code/modules/jobs/job_types/chief_engineer.dm b/code/modules/jobs/job_types/chief_engineer.dm
index bd4732f3c3..c40b3ab821 100644
--- a/code/modules/jobs/job_types/chief_engineer.dm
+++ b/code/modules/jobs/job_types/chief_engineer.dm
@@ -27,8 +27,7 @@
 						ACCESS_HEADS, ACCESS_CONSTRUCTION, ACCESS_SEC_DOORS, ACCESS_MINISAT,
 						ACCESS_CE, ACCESS_RC_ANNOUNCE, ACCESS_KEYCARD_AUTH, ACCESS_TCOMSAT, ACCESS_MINERAL_STOREROOM)
 
-	starting_skills = list(/datum/skill/level/job/wiring = GET_STANDARD_LVL(JOB_SKILL_TRAINED))
-	skill_affinities = list(/datum/skill/level/job/wiring = STARTING_SKILL_AFFINITY_WIRING_ENGI_ROBO)
+	starting_modifiers = list(/datum/skill_modifier/job/level/wiring, /datum/skill_modifier/job/affinity/wiring)
 
 	display_order = JOB_DISPLAY_ORDER_CHIEF_ENGINEER
 	blacklisted_quirks = list(/datum/quirk/mute, /datum/quirk/brainproblems, /datum/quirk/paraplegic, /datum/quirk/insanity)
diff --git a/code/modules/jobs/job_types/chief_medical_officer.dm b/code/modules/jobs/job_types/chief_medical_officer.dm
index 478c33551d..2f115d0166 100644
--- a/code/modules/jobs/job_types/chief_medical_officer.dm
+++ b/code/modules/jobs/job_types/chief_medical_officer.dm
@@ -29,8 +29,7 @@
 	blacklisted_quirks = list(/datum/quirk/mute, /datum/quirk/brainproblems, /datum/quirk/insanity)
 	threat = 2
 
-	starting_skills = list(/datum/skill/numerical/surgery = STARTING_SKILL_SURGERY_MEDICAL)
-	skill_affinities = list(/datum/skill/numerical/surgery = STARTING_SKILL_AFFINITY_SURGERY_MEDICAL)
+	starting_modifiers = list(/datum/skill_modifier/job/surgery, /datum/skill_modifier/job/affinity/surgery)
 
 /datum/outfit/job/cmo
 	name = "Chief Medical Officer"
diff --git a/code/modules/jobs/job_types/cyborg.dm b/code/modules/jobs/job_types/cyborg.dm
index d88d888aec..4f74542b2a 100644
--- a/code/modules/jobs/job_types/cyborg.dm
+++ b/code/modules/jobs/job_types/cyborg.dm
@@ -12,7 +12,7 @@
 	exp_requirements = 120
 	exp_type = EXP_TYPE_CREW
 
-	starting_skills = list(/datum/skill/level/job/wiring = GET_STANDARD_LVL(JOB_SKILL_BASIC))
+	starting_modifiers = list(/datum/skill_modifier/job/level/wiring/basic)
 
 	display_order = JOB_DISPLAY_ORDER_CYBORG
 
diff --git a/code/modules/jobs/job_types/geneticist.dm b/code/modules/jobs/job_types/geneticist.dm
index 4fb989f6e8..f14032348b 100644
--- a/code/modules/jobs/job_types/geneticist.dm
+++ b/code/modules/jobs/job_types/geneticist.dm
@@ -19,7 +19,7 @@
 	display_order = JOB_DISPLAY_ORDER_GENETICIST
 	threat = 1.5
 
-	starting_skills = list(/datum/skill/numerical/surgery = STARTING_SKILL_SURGERY_MEDICAL)
+	starting_modifiers = list(/datum/skill_modifier/job/surgery, /datum/skill_modifier/job/affinity/surgery)
 
 /datum/outfit/job/geneticist
 	name = "Geneticist"
diff --git a/code/modules/jobs/job_types/medical_doctor.dm b/code/modules/jobs/job_types/medical_doctor.dm
index 0e8b2e645b..d77a56d933 100644
--- a/code/modules/jobs/job_types/medical_doctor.dm
+++ b/code/modules/jobs/job_types/medical_doctor.dm
@@ -17,8 +17,7 @@
 	display_order = JOB_DISPLAY_ORDER_MEDICAL_DOCTOR
 	threat = 0.5
 
-	starting_skills = list(/datum/skill/numerical/surgery = STARTING_SKILL_SURGERY_MEDICAL)
-	skill_affinities = list(/datum/skill/numerical/surgery = STARTING_SKILL_AFFINITY_SURGERY_MEDICAL)
+	starting_modifiers = list(/datum/skill_modifier/job/surgery, /datum/skill_modifier/job/affinity/surgery)
 
 /datum/outfit/job/doctor
 	name = "Medical Doctor"
diff --git a/code/modules/jobs/job_types/paramedic.dm b/code/modules/jobs/job_types/paramedic.dm
index e8098daddc..e35fa34cb4 100644
--- a/code/modules/jobs/job_types/paramedic.dm
+++ b/code/modules/jobs/job_types/paramedic.dm
@@ -19,8 +19,7 @@
 
 	threat = 0.5
 
-	starting_skills = list(/datum/skill/numerical/surgery = STARTING_SKILL_SURGERY_MEDICAL)
-	skill_affinities = list(/datum/skill/numerical/surgery = STARTING_SKILL_AFFINITY_SURGERY_MEDICAL)
+	starting_modifiers = list(/datum/skill_modifier/job/surgery, /datum/skill_modifier/job/affinity/surgery)
 
 /datum/outfit/job/paramedic
 	name = "Paramedic"
diff --git a/code/modules/jobs/job_types/roboticist.dm b/code/modules/jobs/job_types/roboticist.dm
index d9e891f057..c6684bb7b1 100644
--- a/code/modules/jobs/job_types/roboticist.dm
+++ b/code/modules/jobs/job_types/roboticist.dm
@@ -16,9 +16,7 @@
 	access = list(ACCESS_ROBOTICS, ACCESS_TOX, ACCESS_TOX_STORAGE, ACCESS_TECH_STORAGE, ACCESS_MORGUE, ACCESS_RESEARCH, ACCESS_MINERAL_STOREROOM, ACCESS_XENOBIOLOGY, ACCESS_GENETICS)
 	minimal_access = list(ACCESS_ROBOTICS, ACCESS_TECH_STORAGE, ACCESS_MORGUE, ACCESS_RESEARCH, ACCESS_MINERAL_STOREROOM)
 
-	starting_skills = list(/datum/skill/level/job/wiring = GET_STANDARD_LVL(JOB_SKILL_TRAINED))
-	skill_affinities = list(/datum/skill/level/job/wiring = STARTING_SKILL_AFFINITY_WIRING_ENGI_ROBO)
-
+	starting_modifiers = list(/datum/skill_modifier/job/level/wiring, /datum/skill_modifier/job/affinity/wiring)
 
 	display_order = JOB_DISPLAY_ORDER_ROBOTICIST
 	threat = 1
diff --git a/code/modules/jobs/job_types/station_engineer.dm b/code/modules/jobs/job_types/station_engineer.dm
index c5280d72db..cc974b5086 100644
--- a/code/modules/jobs/job_types/station_engineer.dm
+++ b/code/modules/jobs/job_types/station_engineer.dm
@@ -18,8 +18,7 @@
 	minimal_access = list(ACCESS_ENGINE, ACCESS_ENGINE_EQUIP, ACCESS_TECH_STORAGE, ACCESS_MAINT_TUNNELS,
 									ACCESS_EXTERNAL_AIRLOCKS, ACCESS_CONSTRUCTION, ACCESS_TCOMSAT, ACCESS_MINERAL_STOREROOM)
 
-	starting_skills = list(/datum/skill/level/job/wiring = GET_STANDARD_LVL(JOB_SKILL_TRAINED))
-	skill_affinities = list(/datum/skill/level/job/wiring = STARTING_SKILL_AFFINITY_WIRING_ENGI_ROBO)
+	starting_modifiers = list(/datum/skill_modifier/job/level/wiring, /datum/skill_modifier/job/affinity/wiring)
 
 	display_order = JOB_DISPLAY_ORDER_STATION_ENGINEER
 
diff --git a/code/modules/jobs/job_types/virologist.dm b/code/modules/jobs/job_types/virologist.dm
index 78f0ba4272..177d8e2b76 100644
--- a/code/modules/jobs/job_types/virologist.dm
+++ b/code/modules/jobs/job_types/virologist.dm
@@ -20,8 +20,7 @@
 
 	threat = 1.5
 
-	starting_skills = list(/datum/skill/numerical/surgery = STARTING_SKILL_SURGERY_MEDICAL)
-	skill_affinities = list(/datum/skill/numerical/surgery = STARTING_SKILL_AFFINITY_SURGERY_MEDICAL)
+	starting_modifiers = list(/datum/skill_modifier/job/surgery, /datum/skill_modifier/job/affinity/surgery)
 
 /datum/outfit/job/virologist
 	name = "Virologist"
diff --git a/code/modules/surgery/surgery_step.dm b/code/modules/surgery/surgery_step.dm
index f574b0aea3..57661901ae 100644
--- a/code/modules/surgery/surgery_step.dm
+++ b/code/modules/surgery/surgery_step.dm
@@ -59,7 +59,7 @@
 	if(tool)
 		speed_mod = tool.toolspeed
 	if(user.mind)
-		speed_mod = user.mind.skill_holder.action_skills_mod(/datum/skill/numerical/surgery, speed_mod, THRESHOLD_COMPETENT, FALSE)
+		speed_mod = user.mind.action_skill_mod(/datum/skill/numerical/surgery, speed_mod, THRESHOLD_COMPETENT, FALSE)
 	if(do_after(user, time * speed_mod, target = target))
 		var/prob_chance = 100
 		if(implement_type)	//this means it isn't a require hand or any item step.
@@ -68,7 +68,7 @@
 
 		if((prob(prob_chance) || (iscyborg(user) && !silicons_obey_prob)) && chem_check(target) && !try_to_fail)
 			if(success(user, target, target_zone, tool, surgery))
-				user.mind?.skill_holder.auto_gain_experience(/datum/skill/numerical/surgery, SKILL_GAIN_SURGERY_PER_STEP)
+				user.mind?.auto_gain_experience(/datum/skill/numerical/surgery, SKILL_GAIN_SURGERY_PER_STEP)
 				advance = TRUE
 		else
 			if(failure(user, target, target_zone, tool, surgery))
diff --git a/tgstation.dme b/tgstation.dme
index dc02385b48..c05877a983 100755
--- a/tgstation.dme
+++ b/tgstation.dme
@@ -289,7 +289,6 @@
 #include "code\controllers\subsystem\minimaps.dm"
 #include "code\controllers\subsystem\minor_mapping.dm"
 #include "code\controllers\subsystem\mobs.dm"
-#include "code\controllers\subsystem\moods.dm"
 #include "code\controllers\subsystem\nightshift.dm"
 #include "code\controllers\subsystem\npcpool.dm"
 #include "code\controllers\subsystem\overlays.dm"
@@ -583,8 +582,11 @@
 #include "code\datums\skills\_check_skills.dm"
 #include "code\datums\skills\_skill.dm"
 #include "code\datums\skills\_skill_holder.dm"
+#include "code\datums\skills\_skill_modifier.dm"
 #include "code\datums\skills\engineering.dm"
 #include "code\datums\skills\medical.dm"
+#include "code\datums\skills\modifiers\job.dm"
+#include "code\datums\skills\modifiers\mood.dm"
 #include "code\datums\status_effects\buffs.dm"
 #include "code\datums\status_effects\debuffs.dm"
 #include "code\datums\status_effects\gas.dm"