Icefeather Aven

Face down, this is a generic 2/2 that reads identically to every other morph on the table, which is exactly the leverage. The morph cost holds a free creature-bounce in reserve, and the card lives in the gap between what a face-down body threatens to be and what this particular one does once the green and blue mana arrives. Turning a face-down permanent up is a special action that doesn't use the stack, so the unmorph itself can't be responded to; the bounce, however, is a triggered ability ("When this creature is turned face up...") that goes on the stack and can be answered like any other trigger. The practical payoff is that the opponent never sees the threat coming until the body flips, and only gets a window to respond once the trigger is already announced. That single hidden line covers a lot of ground: a combat trick that resets a blocker, a tempo swing that returns an opposing creature to hand, or a rescue for one of your own enters-the-battlefield bodies, since the trigger targets another creature and so can't save itself. Read straight, the printed Bird Shaman is unremarkable: a two-mana flyer whose flying is the only thing it advertises. The design is morph used to launder a reactive bounce through the ambiguity of a face-down board, where the answer's value is as much in the bluff as in the resolution.