Hearthpwn

Muligans: Nerubian Egg  Possessed Villager  Haunted Creeper  Bilefin Tidehunter  and Forbidden Ritual

All you need to do is just summon your minions and try to get as much small tokens as possible from your spells or deathrattles so the boss have bigger chance to hit those with hero power. Then just trade his minions when possible or needed , use Power Overwhelming to kill big minions. And slowly push for face when you can, he will run out of cards in few turns.

If you dont have N'Zoth, the Corruptor you can still kill this boss pretty easily.

Also if you dont have some of the cards in the deck , just put some good deathrattle or minions that can summon ohter minions instead of those you are missing.