Anti Teleport

Ok, i'm working on a anti teleport. All the solutions I have come up with crash and dont work for the item Town Hall Teleport. Yes I posted about this but it hasn't been posted in for like 2 weeks.

The Trigger is supposed to detect if a teleport occurs(Mass Teleport, and (Item)Town hall Teleport). Then it supposed to detect if the owner of the Teleporting Unit changes alliance settings from Allied to Enemy within 2 minutes of the Teleporting with the owner of the target unit. If so than the trigger removes all units that were teleported(Units within 700 of triggering unit at time of teleport).

Anyone can think of a way to do this? Or at least give me tips on ways not to make it crash or detecting the target unit of the item use?

What have you done already? Perhaps the 'crash' could be avoided.