Looking to prevent engage with Faction

[lumiya]

Hi everyone I"m in the process of creating an event and I'm looking for ways to prevent players who have a $faction > 9 from engaging the NPCs. I thought about using the Banish code from Vox/Naggy or possibly having them DT anyone who engages and isn't Scowling(faction = 9).

There will be an entire zone full of NPCs with this script on them and I'm not sure if the Banish/DT scripts would cause sever strain on the system or not.

If anyone has an ideas on ways to handle this the help would be greatly appreciated.