Withering Fists (Su): Any creature hit by an ice mummy's slam attacks must make a DC X Fortitude save or take 1d4 points of Strength and Constitution damage. On a critical hit, this damage is instead ability drain. The save DC is Charisma based.
Any reason we've stepped away from the original d12 of damage? Too powerful? These guys have enough powerful abilities that we might as well go whole-hog, give them unholy toughness and a high CR (8-9) to match.
Wow. I just realized I've recommended unholy toughness in my last three posts. Working on the undead will do that.