Hearthpwn

This deck is low tier 2 i think because it has a positive winrate against raza deathknight priest and it can win from midrange hunter if you have good draws. This deck is also fairly budget to make because you can cut the twisting nether. If you get Bloodreaver guldan from the KoFT prologue i highly recommond to play this deck or any deck like this.

With this deck you try to get value and tempo plays from your Ancient watcher, Humongous razorleaf and Devilsaur egg. In combination with your taunt givers this can really put you ahead on the board. 

In the mid game you have the classic Twilight drake and Mountain giant on turn four. If you are playing versus any slow deck any off these on turn four will ussually win you the game. You also have Despicable dreadlord, Abyssal enforcer and twisting nether as insanely powerfull AOW's to hold the board. 

In the late game you can finish off your opponents with bloodreaver guldan, which can bring back 6 demons.

In ungoro, this deck got the amazing addition of Devilsaur egg and Humongous razorleaf. In KoFT in got the finishing touch of Defile, Despicable dreadlord, Bonemare and obviously Bloodreaver guldan, who makes it possible to run the demon package.

Mulligan:

versus Aggro: Mistress of Mixtures, Voidwalker and Defile.

versus Midrange: Mountain Giant, Twilight Drake and Defile. If you are lucky enough to get both a egg or can't attack card in your hand and a taunt giver, you can keep them as well.

versus Control.: Mountain Giant, Twilight Drake and if you are sure you are playing against heavy control you can consider to keep Bloodreaver Guldan too if you already have a Twilight Drake or Mountain Giant.

Playstyle:

Overall this deck has a positive winrate against midrange decks. if you can get a 2 can't attack minions taunted, you win. Against control just try to rush them down and if that doesn't work you always have bloodreaver guldan.