History of CR 506.6

Every distinct wording since 2010, newest first.

June 10, 2022 · Commander Legends: Battle for Baldur’s Gate
Some abilities check to see whether or not a creature “had to attack” during a particular combat phase. A creature had to attack if one or more effects were requiring that creature to attack at the time attackers were declared in that combat. A creature did not “have to attack” if there were no such effects that required it to attack, even if there were no other legal attacks that could have been declared. (See rule 508.)
May 3, 2019 · War of the Spark
Some spells state that they may be cast “only [before/after] [a particular point in the combat phase],” in which that point may be “attackers are declared,” “blockers are declared,” “the combat damage step,” “the end of combat step,” “the combat phase,” or “combat.”
January 25, 2019 · Ravnica Allegiance
Some spells state that they may be cast "only [before/after] [a particular point in the combat phase]," in which that point may be "attackers are declared," "blockers are declared," "the combat damage step," "the end of combat step," "the combat phase," or "combat."
May 1, 2014 · Journey into Nyx
Some spells state that they may be cast “only [before/after] [a particular point in the combat phase],” in which that point may be “attackers are declared,” “blockers are declared,” “the combat damage step,” “the end of combat step,” “the combat phase,” or “combat.”
September 30, 2011 · Innistrad
Some spells state that they may be cast "only [before/after] [a particular point in the combat phase]," in which that point may be "attackers are declared," "blockers are declared," "the combat damage step," "the end of combat step," "the combat phase," or "combat."
June 17, 2011 · Commander 2011
Some spells state that they may be cast “only [before/after] [a particular point in the combat
April 1, 2011 · Duel Decks: Knights vs. Dragons
Some spells state that they may be cast "only [before/after] [a particular point in the combat phase]," in which that point may be "attackers are declared," "blockers are declared," "the combat damage step," "the end of combat step," "the combat phase," or "combat."
February 4, 2011 · Mirrodin Besieged
Some spells state that they may be cast “only [before/after] [a particular point in the combat phase],” in which that point may be “attackers are declared,” “blockers are declared,” “the combat damage step,” “the end of combat step,” “the combat phase,” or “combat.”
October 1, 2010 · Scars of Mirrodin
Some spells state that they may be cast “only [before/after] [a particular point in the combat
February 1, 2010 · Worldwake
Some spells state that they may be cast "only [before/after] [a particular point in the combat phase]," in which that point may be "attackers are declared," "blockers are declared," "the combat damage step," "the end of combat step," "the combat phase," or "combat."