Mulligans
General Mulligans
The only cards i would try to mulligan for would be Barnes and Eternal Servitude. Cheating out any big minion early game will raise your chances of winning by a significant amount, however if you happen to hit Gilded Gargoyle or Shifting shade that is also a decently strong start.
Depending on the Meta this could turn out to be a strong deck, over the past few months i have been playing quest Priest and it is a lot of fun! Be sure to try this out if the meta gears more towards control or tempo, the addition of one single card could make this deck overpowered and Gilded Gargoyle is a great addition to help you cheat out some of the bigger minions and help finish the quest faster.