Nightsky Mimic 
Creature — Shapeshifter
Whenever you cast a spell that's both white and black, this creature has base power and toughness 4/4 until end of turn and gains flying until end of turn.
Legality
standardNOT LEGALpioneerNOT LEGALmodernLEGALlegacyLEGALvintageLEGALcommanderLEGAL