Mulligans
This deck powerful thing in a nutshell goes as follow:
1. Play big Deathrattle minion while having conjurer calling in hand
2. Proc the deathrattle effect with conjurer calling (summoning 1 minions from the deathrattle and 2 from spell). If you play Khadgar you get 2 deathrattle summons and 4 minions from conjurer spell, thats a full board of minions.
3. Most of the times however you will not get this opportunity, but you can drop Khadgar while trading a deathrattle minion and still get 2 summons from it….and then with brewmaster it returns to the safety of your hand (brewmaster can also be used with Janalai, Malacrass, Scorcher or any other minion generated through Conjurer Calling.