[Trigger] Need help with attacking triggers

[conall]

I am working on a multiplayer map that has a neutral hostile race of trolls randomly attacking various players. However, i have a couple problems:

The attacking groups eventually return to their spawn point, and continue to
build up, my attempts to solve this end up crashing the map.

The Attack move command can only affect 12 units at a time, and since the
attacking groups eventually get bigger than this, it contributes to the
buildup

The trolls will not attack buildings

This trigger is supposed to order all the units near the spawn point to attack-move to an enemy unit, and continue looping until there are no units remaining to order. When run it crashes the program. any suggestions or alternate ways to do the same thing would be appreciated.

Unit Group - Order Attackers to Attack-Move To (Position of (Random unit from (Units owned by (Random player from (All enemies of Neutral Hostile)))))

Unit Group - Remove all units of (Units owned by Neutral Hostile matching ((Current order of (Matching unit)) Equal to (Order(attack)))) from Attackers

If ((Number of units in Attackers) Greater than 0) then do (Trigger - Run (This trigger) (ignoring conditions)) else do (Do nothing)