Nerfs and buffs The Traps

🆑 coiax
balance: Wizard traps automatically disappear five minutes after being
summoned.
balance: Wizard traps disappear after firing, whether triggered via
person or something being thrown across it.
balance: Wizards are immune to their own traps.
tweak: The Traps are now marked as a Defensive spell, rather than an
Offensive spell.
/🆑

So a permament structure that has to be beaten down in order to remove
isn't really fun in the long term. So instead, they fire once, and then
disappear. They also disappear after a bit, so they're not long term
hazards, but they do stick around long enough so the wizard can feel
comfortable running back into an area they've already trapped, for that
AREA CONTROL.

code/game/objects/structures/traps.dm

@@ -8,8 +8,10 @@
 	alpha = 30 //initially quite hidden when not "recharging"
 	var/last_trigger = 0
 	var/time_between_triggers = 600 //takes a minute to recharge
+	var/charges = INFINITY
 
 	var/list/static/ignore_typecache
+	var/list/mob/immune_minds = list()
 
 	var/datum/effect_system/spark_spread/spark_system
 
@@ -30,9 +32,11 @@
 	. = ..()
 
 /obj/structure/trap/examine(mob/user)
-	..()
+	. = ..()
 	if(!isliving(user))
 		return
+	if(user.mind && user.mind in immune_minds)
+		return
 	if(get_dist(user, src) <= 1)
 		to_chat(user, "<span class='notice'>You reveal [src]!</span>")
 		flare()
@@ -41,10 +45,15 @@
 	// Makes the trap visible, and starts the cooldown until it's
 	// able to be triggered again.
 	visible_message("<span class='warning'>[src] flares brightly!</span>")
-	alpha = 200
-	animate(src, alpha = initial(alpha), time = time_between_triggers)
-	last_trigger = world.time
 	spark_system.start()
+	alpha = 200
+	last_trigger = world.time
+	charges--
+	if(charges <= 0)
+		animate(src, alpha = 0, time = 10)
+		QDEL_IN(src, 10)
+	else
+		animate(src, alpha = initial(alpha), time = time_between_triggers)
 
 /obj/structure/trap/Crossed(atom/movable/AM)
 	if(last_trigger + time_between_triggers > world.time)
@@ -52,6 +61,12 @@
 	// Don't want the traps triggered by sparks, ghosts or projectiles.
 	if(is_type_in_typecache(AM, ignore_typecache))
 		return
+	if(ismob(AM))
+		var/mob/M = AM
+		if(M.mind in immune_minds)
+			return
+	if(charges <= 0)
+		return
 	flare()
 	if(isliving(AM))
 		trap_effect(AM)