This deck is yet another installation of the Mecha'thun archetype that has been rather effective since its introduction during the Boomsday Project expansion. The idea is to have Mecha'thun and a card that can destroy Mecha'thun immediately on the turn it is played as they only cards you have left on the field, in your hand, and in your deck, in order to meet Mecha'thun's special deathrattle condition and win the game. 

This decklist is pretty standard, carrying a number of removals, healing, and can-trips to cycle you through your deck quickly in order to meet Mecha'thun's deathrattle condition. Having a hero power that allows you to draw a card helps on this front as well. Your combo is to reduce Mecha'thun's cost by at least one by playing Galvanizer with Mecha'thun in hand, and then use either of the 1-cost minion-sacrifice cards on Mecha'thun with just those two cards left over in order to win.