@sentrywiz: As far as i understood he wants some passive units to attack a player if this player is attacking another player while he is inside a specific region. imagine city guards which attack an RPG hero if he attacks another players RPG hero inside the city.
For the trigger, it should look somewhat like this:
(Handwritten!!!)
Trigger:
- Events
- Unit - A unit is attacked
- Conditions
- ((Owner of (Attacked Unit)) Not Equal to (Owner of (Attacking Unit)))
- (MyRect contains (Triggering Unit)
- Actions
- set TempGroup = Units in MyRect matching ((Unit Type of (Matching Unit)) Equal to MyUnitType)
- Unit Group - Pick every unit in TempGroup and do (Actions)
- Loop Actions
- Unit - Order (Picked unit) to Attack (Attacking unit)
- Custom Script: call DestroyGroup (udg_TempGroup)
MyRect would be the rect you are talking about
and MyUnitType would be the unit type of the passive units.