Mulligans
General Mulligans
In general this deck wants ramp and draw early on. Don't keep Nestmatron without ramp, not even against aggro, not even after it gets buffed. Keep Nourish with ramp, and don't be afraid to use it to draw if necessary, even early in the game. Don't keep Finley, even with a hand you'd want on the bottom of your deck. Finley is best played with a full hand so you see more cards and know exactly what's on the bottom of your deck.
Aggro Mulligans
Rising Waves is your game-winning card against aggro. Be careful with Bio Project if you don't have solutions in hand, but in general an early Bio Project is very good against aggro. Think carefully about how much mana you'll have this turn and next turn when you play Bio Project, and what your opponent can do with that mana.
Combo Mulligans
Only keep Razorscale against Rogue; it's not fast enough on its own in any other matchup.
Kazakusan is back! Dragon Druid will see more play when the nerf reverts go through in a couple days and Splish-Splash Whelp becomes playable again, but it’s already meta now. This deck uses Brann/Astalor with Aviana as its primary win condition, with Kazakusan as a backup if the combo gets interrupted or can’t be found fast enough. The new Ysera makes this deck much stronger, as we no longer need Guff or mana refresh to play the full Brann Astalor combo, and we never have to run New Heights again. Floop can copy Kazakusan if you get a bad roll, or just provide another copy of Eonar or Astalor as necessary. He’s even good as an extra Nestmatron against aggro! Mistah Vistah can also increase Kazakusan’s lethality by copying spells like Embers of Ragnaros at the end of the game. E.T.C. contains Theotar for combo interruption, Tight-Lipped Witness for Mage, and The Ceaseless Expanse for Libram Paladin.
I’m not sure what I’ll cut for Splish-Splash Whelp when it goes back to 2 mana. The obvious candidate is Lunar Eclipse, but Lunar Eclipse has been a fantastic tool to control aggro, make Rising Waves work, and dump hand before drawing with Sleep Under Stars. It can even free up our own board spaces to give us room for the Brann Astalor combo! You could cut Razorscale, but you’d be losing a great control tool against Rogues, which I haven’t been seeing much of lately.