Hearthpwn

Hello I am Quatro, Polish player, and I just reached top100 with this deck, the only C'thun deck which work well for me. Later I will add a little guide. 

proof:

 My winratio with this deck 

Something about cards:

Doomsayer - really good synergy with twisting nether in 10 turn, when it's helping us to keep board, also vs aggro when we will play it in 2nd/3rd turn we probably will get board

Spreading Madness - good vs aggro, when opponent have many minions with 1 or 2 hp

Faceless Shambler - really valuable card in late game, when we have taunt 6/6 or even better for 4 mana, it is epic good combo with twilight drake, and also with power overwhelming

The Black Knight - vs druid this card can win game, it is good vs other class too, paladin have tirion, shamans have thing from below etc

I think that other cards  are more standard, but if u have any question why I play any card ask in comments ;)

Something about mathups:

Vs other C'thuns this deck is strong, because we have easy draw from hero power, and decks like c'thun druid or warrior have big problem with it

vs aggro it mainly depends how fast we will get reno, we need to mulligan for him