I don't think I ever boxed them at 90, but if you check my achievement stats, you will see I've cleared the instances >30 times, they are trivial. Agree with the rage winterchill one, same with nax if you dont spread on KT, anub'arak is hard in ToC if you mess your nuke rotation due to %age drain. Basically everything can be killed before any abilities used though.

Collecting every piece of tier gear for all my shammies is some of the most fun ive ever had!! And farming legendaries, I have 3x HoR, just need a 4th haha

EDIT: On souls you can kill yourself if you dps too hard on the dmg reflect stage.