Immediately after the declare attackers step begins, the active player declares attackers. See rule 508.1.
November 19, 2021 · Innistrad: Crimson Vow
Immediately after the declare blockers step begins, the defending player declares blockers. See rule 509.1.
May 3, 2019 · War of the Spark
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.
January 25, 2019 · Ravnica Allegiance
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.
April 27, 2018 · Dominaria
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.
February 1, 2014 · Born of the Gods
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.
September 30, 2011 · Innistrad
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.
June 17, 2011 · Commander 2011
Immediately after the active player has announced damage assignment orders (if necessary)
April 1, 2011 · Duel Decks: Knights vs. Dragons
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.
February 4, 2011 · Mirrodin Besieged
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.
October 1, 2010 · Scars of Mirrodin
Immediately after the active player has announced damage assignment orders (if necessary)
June 18, 2010 · Archenemy
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.
February 1, 2010 · Worldwake
Immediately after the combat damage step begins, each player in APNAP order announces how each attacking or blocking creature he or she controls assigns its combat damage. See rule 510.1.