Urza's Engine | Magic: The Gathering
Formats Urza's Engine is Legal in
Official Oracle Text for Urza's Engine
: Urza's Engine gains banding 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.)
: Attacking creatures banded with Urza's Engine gain trample until end of turn.
Official Rulings for Urza's Engine
10/1/2008 : A maximum of one nonbanding creature can join an attacking band no matter how many creatures with banding are in it.
10/1/2008 : Creatures in the same band must all attack the same player or planeswalker.
10/1/2009 : If a creature in combat has banding, its controller assigns damage for creatures blocking or blocked by it. That player can ignore the damage assignment order when making this assignment.