I almost had a disastrous run as Quest Hunter - got all the way to Millificent, but when I used my DK Shaman hero power it turned a 1-drop into Doomsayer, blowing up my Super Simian Sphere. Luckily I managed to re-stabilize with Shaw+Raptor spam, and once I had board control it was game.

People talk about the Robe of Gaudiness being the best, but since I haven't gotten it so far my absolute MVP treasure is the Hyperblaster - 1/5 Poisonous Immune While Attacking. Clearing five of the toughest minions for free is amazing for tempo.