Cheapest priced copy (Alliances): $0.35 at Card Kingdom, near mint, their price list as of .
Errand of Duty 
Instant · Common · Alliances · #2a
Create a 1/1 white Knight creature token with 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.)
Legal inCommanderLegacyVintagePauper
Not legal inBrawlStandardPioneerModern
2 printings · $0.35 at Card Kingdom
4 rulings from Wizards of the Coast
- 1 October 2008Creatures in the same band must all attack the same player or planeswalker.
- 1 October 2008A maximum of one nonbanding creature can join an attacking band no matter how many creatures with banding are in it.
- 1 October 2008If a creature with banding attacks, it can team up with any number of other attacking creatures with banding (and up to one nonbanding creature) and attack as a unit called a "band." The band can be blocked by any creature that could block a single creature in the band. Blocking any creature in a band blocks the entire band. If a creature with banding is blocked, the attacking player chooses how the blockers' damage is assigned.
- 1 October 2009If a creature in combat has banding, its controller assigns damage for creatures blocking or blocked by it.