Demolish-like spell help

Yes, another thread from me.

I am working on a passive skill for one of my heroes called "Sword of Silver." What it does is allow the hero to deal extra damage whenever he attacks an undead enemy.

With the addition of Demolish, I was thinking I would be able to get away with just changing this skill's allowed targets. Much to my dismay, "undead" was not listed among them.

Could someone lend me a hand getting this annoyingly simple skill to work.

this thread be bumped

Somebody else asked something sort of like this. Make an ability that adds damage to a unit's attack first. Base it off one of the item damage bonus things. Make the damage bonus what u want the extra damage to be. Heres the trigg.

Event-Unit is attacked
Condition-*Integer* Level of Sword of Silver for attacking unit equal to 1.
*Boolean* Attacked unit is undead equal to true
Set AtkUnit equal to Attacking unit *Variable*
Unit-Add (Damage Bonus Ability we made) to AtkUnit
Wait 1 second *Make sure this wait is less than his cooldown, but not too short*
Unit-Remove (Ability) from AtkUnit

This will work.