So this is a rough draft of an OTK (kinda technically TTK) using Metamorphosis and Clockwork Automatons. The combo is there, but I just threw in a bunch of draw cards and removal to fill out the rest of the deck. The combo is pretty simple and doesn't require that many cards to pull off. The most reliable way to get everything at the right cost is to play two Galvanizers on your two Clockwork Automatons to get them to 3 mana. Then play Metamorphosis and wait till your next turn to use your hero power. On this turn, play the two Automatons (6 mana), Garrison Commander (2 mana), and Hero Power your opponent's face twice (1 mana each) for two 20 damage blasts. Skull of Gul'dan is in there just in case you draw one or two of your combo pieces, at which point you could play Thaurrisan to get any remaining pieces to the mana cost you need. They aren't necessarily needed, but they are there to add an extra way to get your combo rolling out faster.