Copycrook is a uncommon Creature — Shapeshifter Rogue card from Modern Horizons 3 (MH3), collector number 55. Current market price: $0.31 (foil $0.33), TCGplayer market prices via Scryfall.
You may have this creature enter as a copy of any creature on the battlefield, except it has "Whenever this creature attacks, it connives." (Draw a card, then discard a card. If you discarded a nonland card, put a +1/+1 counter on this creature.)