Shudderwock C'Thun

C'Thun decks rely on buffing C'Thun and then playing it as a strong late game card. When you add a Shudderwock to a C'Thun deck it allows you to rebuff, replay, and even revive, as if you had played an entire C'thun game in one turn. If you add Zola the Gorgon to your deck and play Shudderwock when it's the only minion on your side of the field, then you even get to repeat that entire chain of events until the game is over.

Start of Game

Early Game

Mid-Game

Late Game