Historical Rules · 14 June 2019
Rule 702.21k
Official source text from the 14 June 2019 Rules release
During the combat damage step, if a blocking creature is blocking a creature with banding, or both a [quality] creature with “bands with other [quality]” and another [quality] creature, the active player (rather than the defending player) chooses how the blocking creature’s damage is assigned. That player can divide that creature’s combat damage as they choose among any number of creatures it’s blocking. This is an exception to the procedure described in rule 510.1d.