If you want something pre-baked, I would take the time to experiment with a system like this
Damage Engine 5.5.0.0 which allows complete GUI utilization of damage detection.
The real event that changes on damage is
DamageEventAmount == 1.00, which you would use to replace your "unit was attacked" event. You can even get fancy and do things
before damage occurs with
DamageEventModifider == 1.00 as the real event.
You can check for
isDamageSpell == true or
DamageEventAttackT == ATTACK_TYPE_HERO etc. to determine attack types.
In your trigger, these values reference the respective units:
DamageEventTarget = unit that was damaged by the attack.
DamageEventSource = unit that attacked.
In your "was attacked" trigger, you could do things for the attacker (DamageEventSource) or the target (DamageEventTarget) by simply using those as the unit variables. If you only want to run a trigger for a specific unit that is attacking, you would include
DamageEventSource == [yourDesiredUnitHere] in the trigger condition.
Again, all of these variables are available in the damage engine via GUI.
