Mulligans
General Mulligans
Look for as much cycle as possible in order to empty your deck and find your other combo pieces.
Aggro Mulligans
Look for board wipes like flurry and sometimes dyn-o-matic. This is one of the bad matchups for the deck, but if you can find an early reckless flurry and a shield block, you should be able to get to the point where you can play your brawls and eventually dr. boom