You can exert him with his ability Bugle Call and pay two ink to play any character for free
While a double-faced card isn't on the stack or battlefield, consider only the characteristics of its front face
You really need to focus on early drops to make this great, but playing this and following it up with something like Hemosymbic Mite, Spyglass Siren, or even just a kicked Pawpatch Recruit, can dominate the early game
Rather, it affects your opponents, so it will also cause any creatures that enter with haste to be required to attack as well
Walker benefits from a sac outlet so that you can generate fliers as and when you need them
Their spells tend to focus on healing or preventing damage, protecting their allies, and neutralizing an opponent's advantages on the battlefield