diff --git a/code/controllers/subsystem/dynamic/__dynamic_defines.dm b/code/controllers/subsystem/dynamic/__dynamic_defines.dm
index f24c772fa24..500666dcd14 100644
--- a/code/controllers/subsystem/dynamic/__dynamic_defines.dm
+++ b/code/controllers/subsystem/dynamic/__dynamic_defines.dm
@@ -43,6 +43,9 @@
 /// Ruleset can be configured by admins (implements /proc/configure_ruleset)
 /// Only implemented for midrounds currently
 #define RULESET_ADMIN_CONFIGURABLE (1<<2)
+/// Applied to rulesets which intentionally share a pref_flag with another rulesets
+/// Denotes multiple rulesets which abide by the same preference, but are each a variation of some base ruleset
+#define RULESET_VARIATION (1<<3)
 
 /// Href for cancelling midround rulesets before execution
 #define MIDROUND_CANCEL_HREF(...) "(<a href='byond://?src=[REF(src)];admin_cancel_midround=[REF(picked_ruleset)]'>CANCEL</a>)"
diff --git a/code/controllers/subsystem/dynamic/_dynamic_ruleset.dm b/code/controllers/subsystem/dynamic/_dynamic_ruleset.dm
index 707c0220ca6..e03f733eb7a 100644
--- a/code/controllers/subsystem/dynamic/_dynamic_ruleset.dm
+++ b/code/controllers/subsystem/dynamic/_dynamic_ruleset.dm
@@ -10,9 +10,12 @@
 	/// Don't change this unless you know what you're doing.
 	var/config_tag
 
-	/// What flag to check for jobbans? Optional, if unset, uses pref_flag
+	/// What flag to check for jobbans?
+	/// Optional, if unset, uses pref_flag for jobbans instead
 	var/jobban_flag
-	/// What flag to check for prefs? Required if the antag has an associated preference
+	/// What flag to check for prefs?
+	/// Required if the antag has an associated preference, and must be unique
+	/// (unless RULESET_VARIATION is set in ruleset_flags)
 	var/pref_flag
 	/// Flags for this ruleset
 	var/ruleset_flags = NONE
diff --git a/code/controllers/subsystem/dynamic/dynamic_ruleset_midround.dm b/code/controllers/subsystem/dynamic/dynamic_ruleset_midround.dm
index b418f1ade42..6df942b5242 100644
--- a/code/controllers/subsystem/dynamic/dynamic_ruleset_midround.dm
+++ b/code/controllers/subsystem/dynamic/dynamic_ruleset_midround.dm
@@ -658,7 +658,7 @@
 	candidate_role = "Changeling"
 	pref_flag = ROLE_CHANGELING_MIDROUND
 	jobban_flag = ROLE_CHANGELING
-	ruleset_flags = RULESET_INVADER
+	ruleset_flags = RULESET_INVADER|RULESET_VARIATION
 	weight = 5
 	min_pop = 15
 	max_antag_cap = 1
@@ -670,6 +670,21 @@
 /datum/dynamic_ruleset/midround/from_ghosts/space_changeling/assign_role(datum/mind/candidate)
 	generate_changeling_meteor(candidate)
 
+/datum/dynamic_ruleset/midround/from_ghosts/space_changeling/mass
+	name = "Mass Space Changelings"
+	config_tag = "Mass Changelings"
+	midround_type = HEAVY_MIDROUND
+	min_pop = 25
+	min_antag_cap = 2
+	max_antag_cap = 3
+	repeatable_weight_decrease = 4
+	weight = list(
+		DYNAMIC_TIER_LOW = 0,
+		DYNAMIC_TIER_LOWMEDIUM = 3,
+		DYNAMIC_TIER_MEDIUMHIGH = 4,
+		DYNAMIC_TIER_HIGH = 5,
+	)
+
 /datum/dynamic_ruleset/midround/from_ghosts/paradox_clone
 	name = "Paradox Clone"
 	config_tag = "Paradox Clone"
@@ -1064,6 +1079,7 @@
 	false_alarm_able = TRUE
 	pref_flag = ROLE_SLEEPER_AGENT
 	jobban_flag = ROLE_TRAITOR
+	ruleset_flags = RULESET_VARIATION
 	weight = 10
 	min_pop = 3
 	blacklisted_roles = list(
@@ -1079,6 +1095,22 @@
 		"[command_name()] High-Priority Update",
 	)
 
+/datum/dynamic_ruleset/midround/from_living/traitor/mass
+	name = "Mass Traitors"
+	config_tag = "Mass Traitors"
+	midround_type = HEAVY_MIDROUND
+	min_pop = 15
+	min_antag_cap = 2
+	max_antag_cap = 4
+	repeatable_weight_decrease = 8
+	blacklisted_roles = list()
+	weight = list(
+		DYNAMIC_TIER_LOW = 0,
+		DYNAMIC_TIER_LOWMEDIUM = 3,
+		DYNAMIC_TIER_MEDIUMHIGH = 8,
+		DYNAMIC_TIER_HIGH = 10,
+	)
+
 /datum/dynamic_ruleset/midround/from_living/malf_ai
 	name = "Malfunctioning AI"
 	config_tag = "Midround Malfunctioning AI"
diff --git a/code/modules/client/preferences/middleware/antags.dm b/code/modules/client/preferences/middleware/antags.dm
index dd81ac44760..39948078b11 100644
--- a/code/modules/client/preferences/middleware/antags.dm
+++ b/code/modules/client/preferences/middleware/antags.dm
@@ -149,11 +149,12 @@ GLOBAL_LIST_INIT(non_ruleset_antagonists, list(
 	for (var/datum/dynamic_ruleset/ruleset as anything in subtypesof(/datum/dynamic_ruleset))
 		var/datum/antagonist/antagonist_type = initial(ruleset.preview_antag_datum)
 		var/antag_flag = initial(ruleset.pref_flag)
-		if (isnull(antagonist_type) || isnull(antag_flag))
+		if(isnull(antagonist_type) || isnull(antag_flag))
 			continue
 
-		// antag_flag is guaranteed to be unique by unit tests.
-		antagonists[initial(ruleset.pref_flag)] = antagonist_type
+		// antag_flag is guaranteed to be unique for all non-RULESET_VARIATION rulesets
+		// the ||= covers specifically those rulesets - prefer the first one over variations
+		antagonists[initial(ruleset.pref_flag)] ||= antagonist_type
 
 	var/list/generated_icons = list()
 
diff --git a/code/modules/unit_tests/dynamic_ruleset_sanity.dm b/code/modules/unit_tests/dynamic_ruleset_sanity.dm
index b42b34f99df..a639fb0f837 100644
--- a/code/modules/unit_tests/dynamic_ruleset_sanity.dm
+++ b/code/modules/unit_tests/dynamic_ruleset_sanity.dm
@@ -30,7 +30,8 @@
 			continue
 
 		if (antag_flag in known_antag_flags)
-			TEST_FAIL("[ruleset] has a non-unique antag_flag [antag_flag] (used by [known_antag_flags[antag_flag]])!")
+			if(!(initial(ruleset.ruleset_flags) & RULESET_VARIATION))
+				TEST_FAIL("[ruleset] has a non-unique antag_flag [antag_flag] (used by [known_antag_flags[antag_flag]])!")
 			continue
 
 		known_antag_flags[antag_flag] = ruleset
diff --git a/config/dynamic.toml b/config/dynamic.toml
index 3d8b6d29655..e5b7f92b2f9 100644
--- a/config/dynamic.toml
+++ b/config/dynamic.toml
@@ -354,6 +354,19 @@ repeatable_weight_decrease = 2
 repeatable = 1
 minimum_required_age = 0
 
+["Midround Mass Changelings"]
+weight.1 = 0
+weight.2 = 3
+weight.3 = 4
+weight.4 = 5
+min_pop = 25
+blacklisted_roles = []
+repeatable_weight_decrease = 4
+repeatable = 1
+minimum_required_age = 0
+min_antag_cap = 2
+max_antag_cap = 3
+
 ["Paradox Clone"]
 weight = 5
 min_pop = 10
@@ -414,6 +427,19 @@ repeatable_weight_decrease = 2
 repeatable = 1
 minimum_required_age = 0
 
+["Midround Mass Traitors"]
+weight.1 = 0
+weight.2 = 3
+weight.3 = 8
+weight.4 = 10
+min_pop = 15
+blacklisted_roles = []
+repeatable_weight_decrease = 7
+repeatable = 1
+minimum_required_age = 0
+min_antag_cap = 2
+max_antag_cap = 4
+
 ["Midround Malfunctioning AI"]
 weight.1 = 0
 weight.2 = 1