Hearthpwn

I'm prettty sure Thijs got about 70% win rate with this deck yesterday (you can check his twitch VOD).

But even if you're not Thijs, this deck is basically a variant of miracle rogue. If you know how to work this deck, it has really good potential (in the right meta, of course). Usually what you would do is use Backstab, SI:7 Agent, Edwin VanCleef etc. for early game removal, board presence and some face damage, then Gadgetzan Auctioneer as a draw machine until you have Malygos, 2x Sinister Strike, and preferably Eviscerate and Emperor Thaurissan. Your big finisher is Malygos and the Sinister Strikes to finish off your oponent, using the emperor to lower the cost of the combo and Preparation + Eviscerate if you need that extra face damage. With Karazhan out you have some nice additions to this deck, in the form of Barnes and Swashburglar. The latter is basically a one mana draw a card and a body on the board, which is very important since otherwise you have no minions on board until turn 3 or 4. And in this deck, pretty much anything coming out of Barnes will be increadibly useful.

Hope this helps. :-)

Edit: Fixed typos in card names.