There seems to be already some form of limiting how many mobs come to agro on a player.
I use the spell Innoruuk's Wrath (
http://lucy.allakhazam.com/spell.htm...19&source=Live) to pull NPCs in a zone and only so many come running to attack me. Once I Destroy (
http://lucy.allakhazam.com/spell.htm...48&source=Live) them, more come running.