Woodlurker Mimic is a common Creature — Shapeshifter card from Eventide (EVE), collector number 130. Current market price: $0.24 (foil $0.66), TCGplayer market prices via Scryfall.
Whenever you cast a spell that's both black and green, this creature has base power and toughness 4/5 until end of turn and gains wither until end of turn. (It deals damage to creatures in the form of -1/-1 counters.)