So… Toe Knee is still bugged. If you just immediately oneshot him at the start, he will keep hitting you at 1hp and the next stage will never come, so unless you are a Hunter to feign death or a Warlock to use the masochistic abilities or some other class that can make it wipe, you’re screwed and need to hearthstone out and run over to Karazhan again.
I mean yeah, you should be careful if you know its bugged and slowly fistfight all the mobs before him and then him so that the fight wont bug, but you won’t always mind to do so.
This “bug” has existed in many dungeons and raids where the player vastly outgears the boss and its mechanics. Killing them too quickly bypasses some of the intended triggers, phases and timers that the specific encounter has which can “break” it… so to speak.
I always find if you standstill and let them hit you (well, it only tickles) a few times before you kill them it tends to be okay.