I don't think the Burning-Tree Emissaries will do much in your deck; they're best for use in the first few turns to get additional 1 or 2 drop creatures out. You don't have many of either. So I would recommend perhaps ditching those, and getting two more Akroan Crusaders and two more Wasteland Vipers.

24 land for a low CMC deck like this seems unnecessary. Perhaps ditch 1-2 Forests for Coordinated Assaults. The first strike ties in well with the Vipers and the bow.

Feral Invocation, while able to be cast at instant speed, isn't very effective. I'd trade them for Madcap Skills. It grants power (ties in with Coordinated Assault) and evasion (ties in with Warriors Lesson). The power also ties in well with Fall of the Hammer.

For your sideboard, Naturalize or Unravel the AEther are better choices than Fade into Antiquity. Cheaper and instant speed are more useful than an exile effect that would only sometimes be needed.

And I think that's all I have for you atm.