diff --git a/common/ruletypes.h b/common/ruletypes.h
index 1a64b1ebd..14288391e 100644
--- a/common/ruletypes.h
+++ b/common/ruletypes.h
@@ -518,6 +518,7 @@ RULE_REAL(Aggro, TunnelVisionAggroMod, 0.75) //people not currently the top hate
 RULE_INT(Aggro, MaxScalingProcAggro, 400) // Set to -1 for no limit. Maxmimum amount of aggro that HP scaling SPA effect in a proc will add.
 RULE_INT(Aggro, IntAggroThreshold, 75) // Int <= this will aggro regardless of level difference.
 RULE_BOOL(Aggro, AllowTickPulling, false) // tick pulling is an exploit in an NPC's call for help fixed sometime in 2006 on live
+RULE_BOOL(Aggro, UseLevelAggro, true) // Level 18+ and Undead will aggro regardless of level difference. (this will disabled Rule:IntAggroThreshold if set to true)
 RULE_CATEGORY_END()
 
 RULE_CATEGORY(TaskSystem)
diff --git a/zone/aggro.cpp b/zone/aggro.cpp
index 847c51e76..4cf403545 100644
--- a/zone/aggro.cpp
+++ b/zone/aggro.cpp
@@ -156,10 +156,21 @@ void NPC::DescribeAggro(Client *towho, Mob *mob, bool verbose) {
 		return;
 	}
 
-	if(GetINT() > RuleI(Aggro, IntAggroThreshold) && mob->GetLevelCon(GetLevel()) == CON_GREEN ) {
-		towho->Message(0, "...%s is red to me (basically)", mob->GetName(),
-		dist2, iAggroRange2);
-		return;
+	if (RuleB(Aggro, UseLevelAggro))
+	{
+		if (GetLevel() < 18 && mob->GetLevelCon(GetLevel()) == CON_GREEN && GetBodyType() != 3)
+		{
+			towho->Message(0, "...%s is red to me (basically)", mob->GetName(),	dist2, iAggroRange2);
+			return;
+		}
+	}
+	else
+	{
+		if(GetINT() > RuleI(Aggro, IntAggroThreshold) && mob->GetLevelCon(GetLevel()) == CON_GREEN ) {
+			towho->Message(0, "...%s is red to me (basically)", mob->GetName(),
+			dist2, iAggroRange2);
+			return;
+		}
 	}
 
 	if(verbose) {
@@ -321,11 +332,12 @@ bool Mob::CheckWillAggro(Mob *mob) {
 	int heroicCHA_mod = mob->itembonuses.HeroicCHA/25; // 800 Heroic CHA cap
 	if(heroicCHA_mod > THREATENLY_ARRGO_CHANCE)
 		heroicCHA_mod = THREATENLY_ARRGO_CHANCE;
-	if
+	if (RuleB(Aggro, UseLevelAggro) &&
 	(
 	//old InZone check taken care of above by !mob->CastToClient()->Connected()
 	(
-		( GetINT() <= RuleI(Aggro, IntAggroThreshold) )
+		( GetLevel() >= 18 )
+		||(GetBodyType() == 3)
 		||( mob->IsClient() && mob->CastToClient()->IsSitting() )
 		||( mob->GetLevelCon(GetLevel()) != CON_GREEN )
 
@@ -344,6 +356,7 @@ bool Mob::CheckWillAggro(Mob *mob) {
 		)
 	)
 	)
+	)
 	{
 		//FatherNiwtit: make sure we can see them. last since it is very expensive
 		if(CheckLosFN(mob)) {
@@ -351,6 +364,39 @@ bool Mob::CheckWillAggro(Mob *mob) {
 			return( mod_will_aggro(mob, this) );
 		}
 	}
+	else
+	{
+		if
+		(
+		//old InZone check taken care of above by !mob->CastToClient()->Connected()
+		(
+			( GetINT() <= RuleI(Aggro, IntAggroThreshold) )
+			||( mob->IsClient() && mob->CastToClient()->IsSitting() )
+			||( mob->GetLevelCon(GetLevel()) != CON_GREEN )
+
+		)
+		&&
+		(
+			(
+				fv == FACTION_SCOWLS
+				||
+				(mob->GetPrimaryFaction() != GetPrimaryFaction() && mob->GetPrimaryFaction() == -4 && GetOwner() == nullptr)
+				||
+				(
+					fv == FACTION_THREATENLY
+					&& zone->random.Roll(THREATENLY_ARRGO_CHANCE - heroicCHA_mod)
+				)
+			)
+		)
+		)
+		{
+			//FatherNiwtit: make sure we can see them. last since it is very expensive
+			if(CheckLosFN(mob)) {
+				Log.Out(Logs::Detail, Logs::Aggro, "Check aggro for %s target %s.", GetName(), mob->GetName());
+				return( mod_will_aggro(mob, this) );
+			}
+		}
+	}
 
 	Log.Out(Logs::Detail, Logs::Aggro, "Is In zone?:%d\n", mob->InZone());
 	Log.Out(Logs::Detail, Logs::Aggro, "Dist^2: %f\n", dist2);