I didn't have high hopes with this deck, but it turns out the buffed SI:7 Smuggler and Crabatoa make Questline Rogue viable in 2022! Well, at least at low ranks (Silver-Gold). But I'm (still) in a 13 win streak, so the deck can't be that bad, right?

Mulligan: easy, keep only the Quest (obviously) and SI:7 Skulker, SI:7 Agent or SI:7 Operative; against Aggro you can consider keeping SI:7 Extortion. Shadowstep if you go second and already have the cheap SI:7 cards. This will help you keep control of the board and make the quest fast.

Your game plan is to develop a healthy board while making the quest, use spells to make efficient trades and finish the game with your big minions and Mr. Smite or spells.

Good luck!