The Reaper King

General Mulligans

Shadow Reaper Auduin is a late game powerhouse that will be the king of finishers once you play Raza the unchained on curve.  Combine Prophet Velen and you will be able to do a massive amount of burst damage at your leisure.  

The Lich King is a card that belongs in every deck this expansion.  His death knight cards are too good.

Barnes is a wonderful RNG card that's fun on early turns and combines well with eternal servitude.  

Obsidian Statue and Spirit Lash are game savers.  Spirit Lash will save you against aggro decks in the early game.