This is my final version of a Treachery Warlock deck. The main goal is to clear board with Hellfire or Abyssal Enforcer until you have a good opportunity to give your opponent either a Howlfiend or an Unlicensed Apothecary. Doomsayer is also very effective with Treachery.
The deck includes other high value minions such as Despicable Dreadlord and some card draw. Two copies of Defile have been included for normal removal an excellent opportunity to discard your opponent's hand with Howlfiend on their side. This is particularly potent against Razakus Priest. Leeroy Jenkins is included for late game burst and also as potential 16 damage combo with your Apothecary.
You want to mulligan any of your potential combo pieces in favor of Mistresses, Loot Hoarders and Hellfires if you are against aggro. Defile is a good keep against Keleseth Rogue or other pirate decks.