all the 'ice' variants of the critters are tougher, I noticed. ;(
Apparently, in TES, "Ice" is like what "Dire" is in D&D - it just means taking a normal creature, and making it have 50 more hit points and deal twice as much damage.
Makes me worry that on some glacier somewhere, an Ice Giant is sitting there, watching his Ice Mammoth graze on deadly ice grass.