Rules glossary
↑ Section 509. Declare Blockers Step
509.1 First, the defending player declares blockers. This turn-based action doesn’t use the stack. To declare blockers, the defending player follows the steps below, in order. If at any point during the declaration of blockers, the defending player is unable to comply with any of the steps listed below, the declaration is illegal; the game returns to the moment before the declaration (see rule 733, “Handling Illegal Actions”).
- 509.1a The defending player chooses which creatures they control, if any, will block. The chosen creatures must be untapped and they can’t also be battles. For each of the chosen creatures, the defending player chooses one creature for it to block that’s attacking that player, a planeswalker they control, or a battle they protect.
- 509.1b The defending player checks each creature they control to see whether it’s affected by any restrictions (effects that say a creature can’t block, or that it can’t block unless some condition is met). If any restrictions are being disobeyed, the declaration of blockers is illegal. A restriction may be created by an evasion ability (a static ability an attacking creature has that restricts what can block it). If an attacking creature gains or loses an evasion ability after a legal block has been declared, it doesn’t affect that block. Different evasion abilities are cumulative. Example: An attacking creature with flying and shadow can’t be blocked by a creature with flying but without shadow.
- 509.1c The defending player checks each creature they control to see whether it’s affected by any requirements (effects that say a creature must block, or that it must block if some condition is met). If the number of requirements that are being obeyed is fewer than the maximum possible number of requirements that could be obeyed without disobeying any restrictions, the declaration of blockers is illegal. If a creature can’t block unless a player pays a cost, that player is not required to pay that cost, even if blocking with that creature would increase the number of requirements being obeyed. If a requirement that says a creature blocks if able during a certain turn refers to a turn with multiple combat phases, the creature blocks if able during each declare blockers step in that turn. Example: A player controls one creature that “blocks if able” and another creature with no abilities. If a creature with menace attacks that player, the player must block with both creatures. Having only the first creature block violates the restriction created by menace (the attacking creature can’t be blocked except by two or more creatures). Having only the second creature block violates both the menace restriction and the first creature’s blocking requirement. Having neither creature block fulfills the restriction but not the requirement.
- 509.1d If any of the chosen creatures require paying costs to block, the defending player determines the total cost to block. Costs may include paying mana, tapping permanents, sacrificing permanents, discarding cards, and so on. Once the total cost is determined, it becomes “locked in.” If effects would change the total cost after this time, ignore this change.
- 509.1e If any of the costs require mana, the defending player then has a chance to activate mana abilities (see rule 605, “Mana Abilities”). (refs: 605)
- 509.1f Once the player has enough mana in their mana pool, they pay all costs in any order. Partial payments are not allowed.
- 509.1g Each chosen creature still controlled by the defending player becomes a blocking creature. Each one is blocking the attacking creatures chosen for it. It remains a blocking creature until it’s removed from combat or the combat phase ends, whichever comes first. See rule 506.4. (refs: 506.4)
- 509.1h An attacking creature with one or more creatures declared as blockers for it becomes a blocked creature; one with no creatures declared as blockers for it becomes an unblocked creature. This remains unchanged until the creature is removed from combat, an effect says that it becomes blocked or unblocked, or the combat phase ends, whichever comes first. A creature remains blocked even if all the creatures blocking it are removed from combat.
- 509.1i Any abilities that trigger on blockers being declared trigger. See rule 509.2a for more information. (refs: 509.2a)