Hi everyone! This is my theory for a Warlock Quest Deck. Really looking forward to give this a try and see if my thoughts hold up in practice!

No pain no gain is the spirit of this deck. By burning through both your deck and hp you will make the opponent take on all your woes and worries!

Game plan:

General: Keep yourself alive whilst completing your quest and burning through your deck to eventually kill your opponent with your own fatigue. Try to use your hero power as often as possible. Unless the opponent is off to a really strong and aggressive start, play the quest on turn 1 and then use your hero power on turn two. 

Against more aggressive decks: Focus on staying alive, by utilising the healing and board clear, whilst trying to move your quest along when you get the chance.

Against slower decks: Really push the quest completion and try to hinder them by burning their important cards. 

Mulligan:

General: I would recommend keeping 1 backfire in your opening hand if are offered it. 

Against more aggressive decks: Look for board clear and healing, for example Hell Fire, Soul Rend, Unstable Shadow Blast, Touch of the Nathrezim or Drain Soul.

Against midrange decks: I'd recommend going for a similar mulligan as against aggro whilst being a bit more greedy with looking for the cards that move the quest along and card draw. Examples of cards that you might be able to get away with keeping against midrange: Tamisen and Soul Stealer.

Against slower decks : Against decks like for example quest priest look for cards that help you move your quest along and burn both your own and the opponents deck. For example: Altar of fire, Soul Stealer, Tamisen and any Backfire you can get. 

Notes and thoughts on specific cards:

Touch of Nathrezim: This seems like a great card to keep your hp from getting to low whilst still giving some board control. Try to make sure that the minion dies to get the healing. 

Demonic Assault: Use this to control the board and stop the opponent from hitting your hero with minions. 

Circus medic: This is a card that works well for you against both slow and aggressive decks. If your are being run down make sure not to corrupt this card and utilise its healing. If you are going up against slower decks then you can even use this to hurt your own hero to really push that quest completion.

Tickatus: In a similar vain as Circus Medic, you don't necessarily want to corrupt Tickatus every game. You can use him as a body on board and as a way to get closer to fatigue. If you are going up against a deck that really suffers from getting cards burned than you still have the option to corrupt him to throw them of their game plan!

Stealer of Souls: I believe this card has the potential to do great things in this Archetype. Playing this and a backfire on turn 7 and then playing the cards you drew might in of it self be enough to more or less complete the quest. If you draw cards like Tickatus or Twisting Nether with this card in play you can also use it as a ton of burst damage and value by playing these high cost cards after playing the final quest reward. 

Final thoughts: I think this archetype and deck will be a ton of fun and also pretty decent/good. Any thoughts or suggestion are more than welcome!