Mulligans
General Mulligans
Play little minions and draw a lot of cards to thin your deck down to dead man's hand and play out the game however you need.
Aggro Mulligans
Get your draw and clears, little minions with high health as well.
Control Mulligans
Draw, armor, and single target removal until you get Dr. Boom down.
DMH your Omega Assembly over and over and get value out of your doctor boom powers. Garrosh is for the odd pally or token druid matchups that you may run into, Dr Boom is good against midrange and control with its infinite vale.