Neutral Passive Attack

In some maps like Sliver's Open RPG I have seen neutral passive units attack. How can I make it so Neutral Passive units will attack?

I'm not sure but it could be through triggers...
If a unit comes close enough then he/she attacks.

Or, it could be that a Team (player team) was made neutral. I never played 'Silver's open RPG' so I don't know what it is exactly.

i believe this trigger is in there, have neutral unally a player or neutral hostile in silver's case