I feel like this guy would be a lot better in a warlock deck where you have enough cards in your hand that you have enough options to not rely on him. In that type of deck it would never be a dead card. Its not something I'd want to topdeck though. I'm really interested in trying him out in a warlock deck after reading this thread.
Turns into yog,clears enemy board, freezes self, and gives me some secrets, including effigy. he dies. effigy drops something big (i forget what) after that i am only like 3 dmg short, pull a raven idol, pull a feral whatever (gives you 4 attack for 3 mana). won the game i would have lost.