Mulligans
General Mulligans
Ideal hand is any combo of Wild Growth, Wrath, Oaken Summons, Ferocious Howl or Nourish.
Since majority of the time you'll need to deck thin and armor gain, Oaken Summons and Branching Paths are great cards to keep.
Aggro Mulligans
If it costs more than 4, swap it.
If it costs less than 4, keep it.
Use Oakheart to cheat out any of your 3 Attack combo cards to allow for Da Undatakah to come in for a massive late game push after another. Generally will lose to aggro but against control it seems to be fine since you don’t have to worry much about fatigue.