Cheapest priced copy (The List): $0.35 at Card Kingdom, near mint, their price list as of .
Aven Liberator 
Creature — Bird Soldier · 2/3 · Common · Scourge · #4
Flying
Morph {3}{W} (You may cast this card face down as a 2/2 creature for {3}. Turn it face up any time for its morph cost.)
When this creature is turned face up, target creature you control gains protection from the color of your choice until end of turn.
Legal inCommanderLegacyVintagePauper
Not legal inBrawlStandardPioneerModern