Hearthpwn

In my opinion, an OTK has to be stealthy. It's extremely important that an OTK deck grabs the win condition without the opponent even noticing and suddenly bring a full-health target to oblivion. The 10 cost limit is quite the challenge, but if it's compact enough, like the now famous Test Subject decks, an unassuming opponent could only watch a firework show before his/her life drops to zero.

Introducing: APM Warlock. Similar to APM Priest, you need quite a lot of APM to get the combo done. It is also more difficult to get a combo of over 30 damage. On the other hand, this is a guaranteed clear board/Reno/huge damage to opponent's face/huge minion on board, so the combo is not completely unusable without the OTK. 

The combo goes:

1. Summoning Portal*2, for 4+2=6 cost

2. Glinda Crowskin, for 2 cost, total 8 cost.

3. Mechwarper, for 1 cost, total 9 cost.

4. Drakkari Enchanter, for 1 cost, total 10 cost.

5. Mechwarper (echo), for 0 cost. All mechs now cost 6 less.

6. Zilliax, for 0 cost. Attach to a Mech Warper.

7. Missile Launcher, for 0 cost. Attach to the same Mech Warper.

8. Repeat 7 until rope burns out.

For damage calculations, Mech Warper+Zilliax is 5/5, and each Missile Launcher is 1 damage to every character and 4/4. Therefore the damage when the resulting Minion (X/X) is (X-5)/2. An ideal combo would result in a Mech Warper of at least 65/65 (65-5=60, 60/4=15, 15*2=30)

Considering situations where combo pieces are missing:

1. Summoning Portal: At least 1 is necessary for board space. If there is only 1, you would have to put Drakkari Enchanter last, which is pretty bad for an APM deck since you do something different at the very end, and with a lot of echo cards in your way.

Also as a sidenote, Summoning Portal+Brann Bronzebeard+Zola the Gorgon(6 cost) could be used if you want a Reno deck.

2. Zilliax: If you have more health than your opponent, it's safe, but you would have to calculate damage. In other situations, you might want to replace some of the cards with Rusty Recycler. This would necessitate 2 Summoning Portals, as well as Drakkari Enchanter last. 

3. Other cards: I do not recommend adding copies of these cards, since most are not linked to your survival. Galvanizer could be used to pretend you're a Mecha'thun Warlock and reduce 1 cost on the first Mechwarper, but there is not much use outside of that. 

You could push an Aggro-style Mech Warlock at the cost of draws, but in this case you could deal quite a lot of damage to the face before the combo. 

If you really love Emperor Thaurissan, you could add an Acolyte of Pain and a Treachery to the combo, which requires 1 tick on 4 cards that are not Mechwarper, Zilliax or Missile Launcher. In this case, the damage calculated above would instead be the number of cards that your opponent draws. With a 65/65 end minion, you would have your opponent draw 30 cards and take 30 damage to the face for an almost guaranteed kill.