diff --git a/common/ruletypes.h b/common/ruletypes.h
index f113834fa..400c5f30f 100644
--- a/common/ruletypes.h
+++ b/common/ruletypes.h
@@ -396,6 +396,7 @@ RULE_BOOL(Spells, UseAdditiveFocusFromWornSlot, false, "Allows an additive focus
 RULE_BOOL(Spells, AlwaysSendTargetsBuffs, false, "Ignore Leadership Alternate Abilities level if true")
 RULE_BOOL(Spells, FlatItemExtraSpellAmt, false, "Allow SpellDmg stat to affect all spells, regardless of cast time/cooldown/etc")
 RULE_BOOL(Spells, IgnoreSpellDmgLvlRestriction, false, "Ignore the 5 level spread on applying SpellDmg")
+RULE_BOOL(Spells, ItemExtraSpellAmtCalcAsPercent, false, "Apply the Item stats Spell Dmg and Heal Amount as Percentage-based modifiers instead of flat additions")
 RULE_BOOL(Spells, AllowItemTGB, false, "Target group buff (/tgb) doesn't work with items on live, custom servers want it though")
 RULE_BOOL(Spells, NPCInnateProcOverride, true, "NPC innate procs override the target type to single target")
 RULE_BOOL(Spells, OldRainTargets, false, "Use old incorrectly implemented maximum targets for rains")
diff --git a/zone/effects.cpp b/zone/effects.cpp
index 86e2422ab..41b8ecd62 100644
--- a/zone/effects.cpp
+++ b/zone/effects.cpp
@@ -284,8 +284,12 @@ int32 Mob::GetActDoTDamage(uint16 spell_id, int32 value, Mob* target) {
 
 int32 Mob::GetExtraSpellAmt(uint16 spell_id, int32 extra_spell_amt, int32 base_spell_dmg)
 {
-	if (RuleB(Spells, FlatItemExtraSpellAmt))
-		return extra_spell_amt;
+	if (RuleB(Spells, FlatItemExtraSpellAmt)) {
+		if (RuleB(Spells, ItemExtraSpellAmtCalcAsPercent))
+			return abs(base_spell_dmg)*extra_spell_amt/100;
+		else
+			return extra_spell_amt;
+	}
 
 	int total_cast_time = 0;
 
@@ -306,6 +310,9 @@ int32 Mob::GetExtraSpellAmt(uint16 spell_id, int32 extra_spell_amt, int32 base_s
 		extra_spell_amt = abs(base_spell_dmg) / 2;
 	}
 
+	if (RuleB(Spells, ItemExtraSpellAmtCalcAsPercent))
+                return abs(base_spell_dmg)*extra_spell_amt/100;
+
 	return extra_spell_amt;
 }