Hey guys, this is my first deck post and I hope you enjoy it. (Sorry for bad English)
The idea is put Mecha'thun + Cataclysm in the same turn after discount its mana.
You can allow the combo by 2 ways:
1) Imperor Thaurissan for 2 turns with the combo pieces in your hand. (Mecha'thun 8 mana + Cataclysm 2 mana)
2) Probably your opponent will kill Thaurissan his first turn, so you need to discount 2 more mana. With Mecha'thun in your hand, play Brann Bronzebeard + Galvanizer to allow the combo.
The second way is more usual, so Brann is a very important card in this deck. You can replace him by Youthful Brewmaster, but isn't recommended. Brann can duplicate other battlecries like card draw, burn opponent card and healing.
Gnomuferatu can win some games burning core cards of yours opponents, like Mecha'thun, Malygos, Antonidas, Shudderwock or any hero card.
Reno is irreplaceable, because against aggro you won't win doing the combo. You only need stay alive until play Bloodreaver Gul'dan. Some players concede immediately when see Reno on board.
Be careful to don't burn your combo pieces and sometimes try to burn opponent cards with Coldlight Oracle.
Feel free to ask or suggest changes