Three times a day, an ice mummy can breath a blast of cold that inflicts 4d6 hp damage to all within its area of effect, a 20’ long cone that is 10’ wide at its base.
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.

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.