Mulligan for cheap stuff and go wide. The boss lacks AoE and you need to beat him fast before he can start playing his Giant army.
Cragtorr has had some issues with Taunts in my matches. He has occasionally used Poison Seeds even though he could've just easily pushed through. So if things seem dire, try playing a Taunt minion and hope the AI has another moment of magic. You probably have nothing to lose anyway at that point.
The games are often decided on how well you can handle his four Shallow Graves. If possible, avoid playing large value minions until he plays the card, that way his minion pool contain only weaker minions.
When playing Tess you'll win right from the start by using her Hero Power before playing any other spells. Your Small Rock will get echo which allows you to play infinite amount of them. The same idea applies to Toki with Arcane Missiles and Khadgar's Scrying Orb.
Thanks for the info! I actually played one run after the latest nerfs for quest and was annoyed because the older version of the deck also had Mana Wyrm and I felt Toki was the weakest one already. I wonder if that's the reason for deck update or if they changed something else too.