how to prevent npc attacks

[Mariomario]

Probably not the best suggestion as this would trigger the entire time during combat against the passive object, but it would do exactly as needed. Your passive object would start with the needed flags fUCNIDo then inside of a script:

sub EVENT_COMBAT
{
	if($combat_state == 1)
	{
		quest::modifynpcstat("special_attacks",fUCNIDoH);
		$npc->WipeHateList();
	}
}

This would allow the aggressive mobs to assist the passive object upon initial attack, then sets the passive object back to non-aggro and wipes the hate list stopping it from attacking the original toon who attacked it. Again probably not the best suggestion, but it achieves what you're looking for.