This deck is good, but VERY difficult to play. Regular zoolock is not great at the moment. This version is a little worse at zoo-ing, but the Mecha'thun combo allows it to win many many games that normal zoolock looses. The combo is:

1. Use Galvanizer to reduce Mecha'thun by at least 1
2. Empty deck and hand other than combo cards
3. Play Mecha'thun and Plague of Flames (or Grim Rally with an empty board)

Mulligan:

• Keep: Any lackey related cards, especially Dark Pharaoh Tekahn. Also keep Scarab Egg, other  1-drops for sacrificing
• Toss: Galvanizer, Mecha'thun, Plague of Flames, Grim Rally

General strategy

• We want to build a board as fast as possible and keep the opponent on defense.
• As long as you are not way behind on the board, after turn 4 or so, hero power as often as possible for draw
• Plague of Flames is amazing in this deck. Wish we had more. While technically you can pull off the combo with Grim Rally, it's way harder. Don't rely on that. Do all you can to save both Plague of Flames. Its also useful as board clear right before the combo if you have both. Always take them if offered from the lackey. You can never have enough.
• Cult Master is also essential for this deck, but hard to use. Try to combo with Scarab Egg and cards that sacrifice your own minions. Be careful not to overdraw unless you have the combo piece
• When you get down to 3-4 cards left in the deck, STOP DRAWING other than hero power. Kill off any Cult Master. You need to start emptying your hand. You don't want to have an empty deck with too many cards to get rid of in hand, so you die to fatigue damage

Matchups that I see fairly often:

Control Warrior: Good. Warrior will think you are playing zoo and not see the Mecha'thun combo coming. Just keep drawing and make sure not to lose any combo cards. Keep pushing tempo to keep opponent on defense. Try to save your non-combo Plague of Flames for when the big taunts come out near the end.

Murloc Paladin: Good. You win by Fatigue, don't worry about the Mecha'thun combo. You should have enough tempo to hold off the murloc swarms unless you get really unlucky. Make sure you keep 1 Plague of Flames, along with enough small minions (keeping a Scarab Egg and sacrifice card really helps) for the very end so that you can deal with Chef Nomi. Or look for a Twisting Nether from a lackey. Either way, when you kill the Chef Nomi board, the opponent will concede.

Rogue: Good. This match-up is an RNG fiesta, but just keep working on the draw and you'll win with the Mecha'thun combo.

Mage: Good. Try to kill giants with minions and other spells first. If you can't, take damage for a turn, let them waste Conjurer's Calling and then play your the non-combo Plague of Flames.

Quest Priest: Good. You should be able to win with the Mecha'thun combo. Save the non-combo Plague of Flames for Mass Resurrection, and otherwise do your best to prevent priest from drawing cards.

Quest Shaman: Okay. This one is always a close match. Keep pushing hard to make the opponent play defense until you can get the combo out. Occasionally, you'll win without the combo.

Quest Druid: Okay. Another often close one. You'll win with the Mecha'thun combo. Save the non-combo Plague of Flames for a turn where a bunch of big choose-one stuff comes out.

Zoolock: Difficult. This is a tough matchup. Their deck is a little better at zoo than ours. Try your best to kill Magic Carpet ASAP, or things spiral out of control. (NOTE: Same goes for the similar zoo Paladin)

Highlander Hunter: Worst. This one is really hard. If hunter gets a decent draw, they'll kill you by turn 7-8. Avoid damage at all costs and hope for the best.