How to make an ability only damage undead?

Not the undead race, but if a unit is classified as undead, I want something to do damage to only that type of units. Is there an easy way? (Using SLK's)

I think u can make this with a normal boolean trigger.
((Triggering unit) is Undead) Equal to True

Dark Ritual and Death Pact can only target units with an undead tag. Have one of those two able to target enemy units. Make the tooltips of this ability be the ones of the ability you want it to be, then give them the ability you want to only effect undead and hide it by pushing it off of the commands list. Then have a trigger that whenever the dark ritaul/death pact is orderred, it will make the unit cancel that order and instead cast the hidden actual spell on the target that was chosen. This way, a non undead target will force it to say "Must target Undead Unit" (Actually I think it will say "Must Target Friendly Undead Unit" but I think you can change the message in game constants.), and if the target IS undead, it will force the unit to cast a different spell on the same target. If the spell effects units other than the target, like chain lightning, ... then your gonna have problems... But if it's a single target spell this should help!

edit the targets

In the TFT WE, just add the 'Undead' flag to the allowed targets field.

Is there any ability out there that just allows 'living' units.

doubledare, unded isn't one of the target options for the target list, nor is living, summoned, etc....

the undead/living/summoned targets used to be available through SLK editing before TFT, but they seem to have been removed :/

Isn't it possible to make Holy Light just target enemies?

Probably, just change the targets id think or maybe edit a spell which is enemy only and put the Holy light properties in.

Tirias

The easiest way would be to make a new spell using Holy Light as the base for it, then edit the graphics/tool tips/damage accordingly for the spell you want to make.

Yeah I realized that holy light is hard coded to attack undead, so I just set the target to enemy and it works. Thanks.