Mishra's War Machine (Summer Magic / Edgar 266) - Rare Magic: The Gathering Card

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 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.)
At the beginning of your upkeep, this creature deals 3 damage to you unless you discard a card. If it deals damage to you this way, tap it.