[Graeme Dice]

Originally posted by Argitoth:
A massive damaging fire, heat, cold, or electric attack would work. You never said Doom Horrors were immunute to the elements.

That's what blood vengeance is for. Casting a spell on hit will cause your own unit the damage if it fails a magic resist check against a penetration bonus of 2. If it does get hurt, it can heal itself back up against non-lifeless targets with lifedrain. Put an amulet of antimagic and a regeneration item on it for good measure.