Adds ModifyResistances proc and fixing spelling error

code/modules/mob/living/simple_animal/abnormality/he/doomsday_calendar.dm

@@ -305,7 +305,7 @@
 		adjustBruteLoss(100)
 		pulse_damage -= 1
 		playsound(get_turf(src),'sound/abnormalities/doomsdaycalendar/Limbus_Dead_Generic.ogg', 50, 1)
-		AddModifier(/datum/dc_change/sacrified)
+		AddModifier(/datum/dc_change/sacrificed)
 
 //***Simple Mobs***//
 //clay dolls

code/modules/mob/living/simple_animal/damage_coeff_helper.dm

@@ -141,3 +141,30 @@
 			if(istype(DC, mod))
 				return DC
 
+
+/**
+ * Modify a group of resistances by a custom amount.
+ * Note: This is permanent unless the returned DCs are kept and removed semi-manually later.
+ * Using the other procs and making a custom dc_change datum is preferable to this, along with tying it to a status effect.
+ *
+ * vars:
+ * * target - a simple animal
+ * * changes - an associated list of damage types and values (RED_DAMAGE = 1.2, WHITE_DAMAGE = 0.8, ...)
+ * * additive - TRUE if the values should be added/subtracted to the damage_coeff or FALSE if used multiplicatively.
+ *
+ * returns: A list of DC_Changes if successful, otherwise FALSE.
+ */
+/proc/ModifyResistances(mob/living/simple_animal/target, list/changes = list(), additive = FALSE)
+	if(!target || !LAZYLEN(changes))
+		return FALSE
+	. = list()
+	for(var/DT in changes)
+		var/datum/dc_change/DC = new
+		DC.additive = additive
+		DC.potency = changes[DT]
+		DC.damage_type = DT
+		. += DC
+	target.damage_mods += .
+	target.UpdateResistances()
+	return
+

code/modules/mob/living/simple_animal/dc_changes.dm

@@ -37,7 +37,7 @@
 	damage_type = PALE_DAMAGE
 
 /// +0.1 Universal modifier, self-inflicted by Doomsday calender
-/datum/dc_change/sacrified
+/datum/dc_change/sacrificed
 	additive = TRUE
 	potency = 0.1
 	damage_type = list(RED_DAMAGE, WHITE_DAMAGE, BLACK_DAMAGE, PALE_DAMAGE)