Metallic Mimic is a rare Artifact Creature — Shapeshifter card from Aether Revolt (AER), collector number 164. Current market price: $3.22 (foil $5.26), TCGplayer market prices via Scryfall.
As this creature enters, choose a creature type. This creature is the chosen type in addition to its other types. Each other creature you control of the chosen type enters with an additional +1/+1 counter on it.