How did you go about it? Personally, I simply ran a gimmick priest deck. You know the deal - divine spirit, inner fire, big HP taunts, the shizz. Instructor was rather easy - thoughtstole two of his weapons on third attempt, all I had to do from then on was put up a wall of taunted HP for him to go through that lasted a few turns. Gothik took a very similar deck - a huge wall of taunts, with a bunch of Pyros, Aboms, and the CoH combo to get rid of the spectral guys until I needed them. Once the board was comfortable, slam the combo on something with high HP - for me it was a Spectral Rider leftover after clearing - and smash his face in. And the Four Horsemen - oh so surprisingly - took... a huge wall of taunts and aoe effects until a 16/16 Deathlord slammed into Rivendare's face like a sledgehammer.
Honestly, this HC quarter was kinda boring. In the other two at least last bosses were fun little puzzles - here it was just a roll of dice until my starting hand had what was necessary into cruise control to victory. Doing the entire thing, from opening the wing to class challenges, normal and heroic 100% cleared took me about 40 minutes - and that's with concedes after an unfavourable draft.