500. Legal Attacks and Blocks
Some effects restrict declaring attackers or blockers in combat or require certain creatures to be
declared as attackers or blockers. (See rule 308, “Declare Attackers Step,” and rule 309, “Declare
Blockers Step.”) A restriction is an effect that says a creature can’t block (or attack) or it can’t
block (or attack) unless some condition is met. A requirement is an effect that says a creature must
block (or attack) or it must block (or attack) if some condition is met.
As part of declaring attackers, the active player checks each creature he or she controls to see
whether it must attack, can’t attack, or is affected by some other attacking restriction or
requirement. If such a restriction or requirement conflicts with the proposed attack, the attack is
illegal, and the active player must then propose another set of attacking creatures. (Tapped creatures
and creatures with unpaid costs to attack are exempt from effects that would require them to attack.)
Example: A player controls two creatures, each with a restriction that states “[This
creature] can’t attack alone.” It’s legal to declare both as attackers.
Example: A player controls two creatures: one that “attacks if able” and one with no
abilities. An effect states, “No more than one creature can attack each turn.” The only legal
attack is for just the creature that “attacks if able” to attack. It’s illegal to attack with the
other creature, attack with both, or attack with neither.
As part of declaring blockers, the defending player checks each creature he or she controls to see
whether it must block, can’t block, or is affected by some other blocking restriction or requirement.
If such a restriction or requirement conflicts with the proposed set of blocking creatures, the block is
illegal, and the defending player must then propose another set of blocking creatures. (Tapped
creatures and creatures with unpaid costs to block are exempt from effects that would require them
An evasion ability is an ability an attacking creature has that restricts what can block it.
Evasion abilities are static abilities that modify the declare blockers step of the combat phase. If
a creature gains or loses an evasion ability after a legal block has been declared, it doesn’t affect
that block. Evasion abilities are cumulative.
Example: A creature with flying and shadow can’t be blocked by a creature with flying
but without shadow.
500.4. A restriction conflicts with a proposed set of attackers or blockers if it isn’t being followed. A
requirement conflicts with a proposed set of attackers or blockers if it isn’t being followed and (1)
the requirement could be obeyed without violating a restriction and (2) doing so will allow the total
number of requirements that the set obeys to increase. If there are multiple scenarios in which all
restrictions are being followed and the maximum possible number of requirements are being
followed (even if not all of them are), then any of those scenarios are legal.
Example: A player controls one creature that “blocks if able” and another creature with no
abilities. An effect states, “Creatures can’t be blocked except by two or more creatures.”
Having only the first creature block violates the restriction. Having neither creature block
fulfills the restriction but not the requirement. Having both creatures block the same
attacking creature fulfills both the restriction and the requirement, so that’s the only option.