Immediately after the combat damage step begins, each player in APNAP order announces how each attacking or blocking creature they control assigns its combat damage. See rule 510.1.
October 7, 2022 · Unfinity
Immediately after blockers have been declared during the declare blockers step, for each attacking creature that’s become blocked by multiple creatures, the active player announces the damage assignment order among the blocking creatures. See rule 509.2.
November 19, 2021 · Innistrad: Crimson Vow
Immediately after the active player has announced damage assignment orders (if necessary) during the declare blockers step, for each creature that’s blocking multiple creatures, the defending player announces the damage assignment order among the attacking creatures. See rule 509.3.
April 27, 2018 · Dominaria
Immediately after the combat damage step begins, each player in APNAP order announces how each attacking or blocking creature they control assigns its combat damage. See rule 510.1.
September 30, 2011 · Innistrad
Immediately after combat damage has been assigned during the combat damage step, all combat damage is dealt simultaneously. See rule 510.2.
June 17, 2011 · Commander 2011
Immediately after combat damage has been assigned during the combat damage step, all
February 4, 2011 · Mirrodin Besieged
Immediately after combat damage has been assigned during the combat damage step, all combat damage is dealt simultaneously. See rule 510.2.
October 1, 2010 · Scars of Mirrodin
Immediately after combat damage has been assigned during the combat damage step, all
June 18, 2010 · Archenemy
Immediately after combat damage has been assigned during the combat damage step, all combat damage is dealt simultaneously. See rule 510.2.
February 1, 2010 · Worldwake
Immediately after the cleanup step begins, if the active player's hand contains more cards than his or her maximum hand size (normally seven), he or she discards enough cards to reduce his or her hand size to that number. See rule 514.1.