What about playing an 80/80-ish damage C'Thun ?

That usually kills both the board and the opponent.

THe plan : Play C'THun buffers while completing the quest during the early game, once you have both Shudderwock and C'Thun in hand, play Fencing Coach the turn before Shudderwock. Next turn enjoy a huge C'Thun with a double battlecry that rarely find enough resistance on the opponent's side to prevent lethal.