: Urza's Avenger 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.)