An OTK (technically two turns) combo based on the new Shadow of Death card. There are a few steps but if done correctly, it would provide a 36-damage combo.

1. Play a Novice Engineer and Shadowstep it.
2. Draw Leeroy Jenkins, Myra's Unstable Element, both copies of Shadow of Death, and both copies of Preparation.
3. Use Myra to draw the rest of your deck.
4. On the next turn, play Leeroy and use both Preps to cast both Shadow of Deaths on him.
5. Use the Shadowstepped Engineer to draw and summon 5 additional Leeroys.
6. Win.

There are other ways to play this deck. In Wild, Emperor Thaurissan could let you play the whole combo on one turn, and if you could keep him alive for two turns you could use Shiv to get an extra Leeroy for a 42-damage combo.

I'm sure there are better ways to build the rest of the deck, and maybe better ways to play the combo, but let me know what you think and how you would improve it!