506.8 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.”
506.8a
A spell that states it may be cast “only before (or after) attackers are declared” is referring to the turn-based action of declaring attackers. It may be cast only before (or after) the declare attackers step begins, regardless of whether any attackers are actually declared. (See rule 508.)
(refs: 508)
506.8b
A spell that states it may be cast “only before (or after) blockers are declared” is referring to the turn-based action of declaring blockers. It may be cast only before (or after) the declare blockers step begins, regardless of whether any blockers are actually declared. (See rule 509.)
(refs: 509)
506.8c
Some spells state that they may be cast only “during combat” or “during a certain player’s combat phase” in addition to the criteria described in rule 506.8. If a turn has multiple combat phases, such spells may be cast at an appropriate time during any of them.
(refs: 506.8)
506.8d
Some spells state that they may be cast “only before (or after) [a particular point in the combat phase],” but don’t meet the additional criteria described in rule 506.8c. If a turn has multiple combat phases, such spells may be cast that turn only before (or after) the stated point of the first combat phase.
(refs: 506.8c)
506.8e
If a spell states that it may be cast “only before [a particular point in the combat phase],” but the stated point doesn’t exist within the relevant combat phase because the declare blockers step and the combat damage step are skipped (see rule 508.8), then the spell may be cast only before the declare attackers step ends. If the stated point doesn’t exist because the relevant combat phase has been skipped, then the spell may be cast only before the precombat main phase ends.
(refs: 508.8)
506.8f
If a spell states that it may be cast “only during combat after blockers are declared,” but the declare blockers step is skipped that combat phase (see rule 508.8), then the spell may not be cast during that combat phase.
(refs: 508.8)
506.8gRules 506.8 and 506.8a–f apply to abilities that state that they may be activated only at certain times with respect to combat just as they apply to spells that state that they may be cast only at certain times with respect to combat.
(refs: 506.8)