We'll want to run the usual suspects like Rampant Growth, Kodama's Reach, Explosive Vegetation, and the decision of whether or not to run mana rocks will probably be a meta call
Fuck the legendary cards they suck
While some hyper efficient, single-target interaction like countermagic and Path to Exile is useful, you should also invest in cards like Grasp of Fate, Soul Shatter, and Convert to Slime to keep ahead on cards while putting your opponents behind on the board
When you scratch your head and think "How the heck am I going to win with Squirrels?!?", think Overrun, Centaur Chieftain, or even Lure
doing the best with what you've got
Angel's Grace Celestine Reef Cloudsteel Kirin Courageous Resolve Gideon of the Trials Herald of Eternal Dawn Lich's Mastery Liliana's Other Contract (double-faced)(playtest) Platinum Angel Platinum Angel Avatar The Book of Exalted Deeds