One of the more interesting cards from the Kobolds and Catacombs expansion is Azari, the Destroyer.
It’s Battlecry is: Destroy your opponent’s deck.
It’s not easy to get this card in-hand though, you need to play 5 Seal’s beforehand with a total of 25 mana, then play the card for 10 mana.
These are the seal cards:
As you can see you do get a Demon with every seal you play too. The cost does seem a little high right now, but it’s always hard to gauge new cards before we’ve seen the whole set.
Certainly, some theory crafting ideas for control Warlock decks. Destroying your opponent’s deck is a powerful mechanic and will put them straight into fatigue.