Cooperation | Magic: The Gathering
Formats Cooperation is Legal in
Official Oracle Text for Cooperation
Enchanted creature has banding. (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 a player controls are blocking or being blocked by a creature, that player divides that creature's combat damage, not its controller, among any of the creatures it's being blocked by or is blocking.)
—General Jarkeld, the Arctic Fox
Official Rulings for Cooperation
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.