Urza's Avenger is a rare Artifact Creature — Shapeshifter card from Antiquities (ATQ), collector number 74. Current market price: $14.58, TCGplayer market prices via Scryfall.
{0}: This creature gets -1/-1 and gains your choice of banding, flying, first strike, or trample until end of turn. (Any creatures with banding, and up to one without, can attack in a band. Bands are blocked as a group. If any creatures with banding you control are blocking or being blocked by a creature, you divide that creature's combat damage, not its controller, among any of the creatures it's being blocked by or is blocking.)