The idea of this deck is simple: clear your deck, hand and board as soon as possible to be able to play a combination of Mecha'thun , Naturalize and Innervate. In order to survive till the combo there are some taunts in the deck to tank damage and there are plenty of spells to kill off minions, like Lesser Jasper Spellstone , Wrath and Swipe. Besides this, there are several ways of gaining armor.
Mulligan for the early ramp like Wild Growth and Greedy Sprite. Try to get mana early so you can draw cards and clear the enemy board in the mid game. Overdrawing is fine, just make sure you have an Innervate, a Naturalize and a Mecha'thun in your hand. Once you are close to the end of your deck start emptying your hand and killing off your own remaining minions so the Mecha'thun deathrattle works. Since the win condition is Mecha'thun there is no reason to go face with anything, focus on clearing the board and surviving.