Mulligan: Try and mulligan for your early game clears Penance, Forbidden Words, andShadow Word: Pain.

Try and mulligan for Mass Dispel to help you with Toxic Reinforcements and Necrium Apothecary also Zilliax is your friend here. Zilliax followed by Psychopomp can keep you out of trouble. If you are going up against a deck that likes to fill the board with low health minions Breath of the Infinite can help you reach the end game.

Midgame: Once you get past the first few turns blasting away minions with Penance and Shadow Word: Pain its time to start building board presents and getting your res pool nice and spicy. Convincing Infiltrator, Khartut Defender, and Zilliax are a good start if you can sneak in a Spirit of the Dead along side a few reborn minions you can start working towards a big hand refill with Bwonsamdi, the Dead

Endgame: Ideally you want to get out your [Hearthstone Card (zereks cloning gallery) Not Found] on turn 9 or coin out on 8 .If you ever get into a bit of trouble Plague of Death can clear the way for Mass Resurrection. Again Mass Res plus Spirit of the Dead can refill your deck for those long games. If Zereks doesn't get out your Hakkar, the Soulflayer out as soon as possible, most players try and get rid of it instead of attacking your health. 

If you try this deck feel free to give feedback. This is my first build