Historical Rules · 13 November 2015
Rule 702.21j
Official source text from the 13 November 2015 Rules release
During the combat damage step, if an attacking creature is being blocked by a creature with banding, or by both a [quality] creature with “bands with other [quality]” and another [quality] creature, the defending player (rather than the active player) chooses how the attacking creature’s damage is assigned. That player can divide that creature’s combat damage as he or she chooses among any number of creatures blocking it. This is an exception to the procedure described in rule 510.1c.