How it works:

Summon Highkeeper Ra for 20 damage to the face: You need Emperor Thaurissan, Glinda Crowskin, 2xMogu Cultist and Grim Rally to be in your hand. "Tick" on Glinda, 2xCultist and Rally with Emperor, to reduce their mana cost by (1). Next turn play Glinda (5 mana) + Cultist (0 mana) + 5xCultist (5 mana) + Rally on Glinda (0 mana) + last Cultist (0 mana), to summon Highkeeper Ra (10 mana) and deal 20 damage to your opponent's face and board.

During the early/mid game survive by playing Lackey synergies and trading efficiently, while filling your hand with cards like EVIL Genius, EVIL Cable Rat etc. Your combo pieces become "dead" draws and clog your hand, so cards like Twilight Drake and Mountain Giant benefit from this. Using Life Tap mid game helps a lot in this direction and helps you assemble your combo pieces faster.

After Emperor ticks on your hand and you are about to go off, you can firstly play Plague of Flames for 0 mana at the start of your next turn to clear your remaining board.

Replacements:

Warlocks have many premium surviving tools available at their disposal, so you can pick your favorites. Twisting Nether, Siphon Soul and Doomsayer could be useful here. When the event begins, I'll test how good another copy of Plague of Flames could be. All-around cards like SN1P-SN4P (which synergises well with Zilliax), Siamat and N'Zoth, the Corruptor could be used as well, but the deck might need some adjustment then.

Mulligan:

Always mulligan for Lackey card generators and synergies, Mortal Coil and if on Coin keep Mountain Giants as well. If you are positive you face an aggro deck, keep a copy of Hellfire in your hand.

PS: If you are up for it, check my refined Wild OTK version too!

Edit: All the combo pieces needed to summon Highkeeper Ra are in a way of Legendary rarity, because you cannot miss any of them in order to go off. On top of that, you have the Emperor Thaurissan "dead" turn and you are forced to use Life Tap, draining some of your life total. That's why it is imperative that you stall the game enough, while having adequate board presence, pushing for some face damage and gaining a bunch of life back.

Thankfully, there are premium healing minions with Deathrattle and Taunt that are way too important to ignore, so I switched to a N'Zoth, the Corruptor package and I'm having a great time with it so far! Be careful when playing him though, because summoning Bloodmage Thalnos while having a full hand can mill a combo piece.

Keep in mind that the lackeys are more useful to keep your hand and mana curve in check, rather than pushing for face damage. They make Plague of Flames an incredible card in this deck (especially Faceless Lackey), so use them carefully. I have found that Shadowflame works well with Giants and big dudes, so I might be dropping Twisting Nether for another copy of it in the future.

Anyways, here is how it went for me a few days after the event went live: