Quest Demonlock (Scholomance Academy)

Mostly any card that is 3 mana or less is viable to mulligan for. Spirit Jailer and Ebonlocke are good proactive early game drops. The early game removal is good for keeping initial enemy board states in check. Dark Skies and is almost always a full clear for most boards by turn 3. It can range anywhere between 2 - 7 damage depending on who has 2nd turn w/ coin as well as your early game choices. Plot twist is another good mulligan if your enemy does not have proactive plays. It gives you the option to complete your quest faster without too much punishment, as well as allowing you to search for proactive cards that you can play in the midgame if you didn't have them already.

Spirit Jailer is a great card to mulligan for against aggro because its stat line allows it to stick on board for potential trades. Soul Shear is great against 2 drop plays and is even better when Spirit Jailer is still in play. School Spirits and Doomsayer are good against wide board states generated by classes like Tempo Demon Hunter, Aggro Rogue, and and Token Druid. The main idea with these mulligans is to stall until the midgame without taking too much damage so that you have plays like Void Drinker and Abyssal Summoner to help you stabilize and make your Ebonlocke setup better.