Battlegate Mimic is a common Creature — Shapeshifter card from Eventide (EVE), collector number 133. Current market price: $0.08 (foil $2.60), TCGplayer market prices via Scryfall.
Whenever you cast a spell that's both red and white, this creature has base power and toughness 4/2 until end of turn and gains first strike until end of turn.