I got diamond 4 from reset so far in 1 day with this deck = https://gyazo.com/833718de5482addd0fd2cfe301bee815
81% winrate in 32 games (26 wins)
Crazy control anti meta deck with devestating momentum changes, and a maive for stalling enemy big minions for when your ready to board clear, or if you want to hide Kel'thuzad for two turns so the enemy wont want to put more minions on the board, wave of aparthy for stalling and board clear.
Essentually you delay for ages, constantly board clear, samuro + apotheosis for massive heal and board clear, maiev to delay large minions being put down in early rounds so you have time to setup board clear or Headmaster Kel'thuzad, or to hide Kel'thuzad to get a better clear.
C'thun for a win condition if your momentum doesn't win for you.
#3 upvotes for indepth guide
#5 upvotes for mulligan vs every class
#7 upvotes for indepth video guide