420.1. State-based effects are a special category that apply only to those conditions listed below. Abilities that watch for a specified game state are triggered abilities, not state-based effects. (See rule 404, "Triggered Abilities.") 420.2. State-based effects are always active and are not controlled by any player.

420.3. Whenever a player would get priority (see rule 408, "Timing of Spells and Abilities"), the game checks for any of the listed conditions for state-based effects. All applicable effects resolve as a single event, then the check is repeated. Once no more state-based effects have been generated, triggered abilities go on the stack, and then the appropriate player gets priority. This check is also made during the cleanup step (see rule 314); if any of the listed conditions apply, the active player receives priority.

420.4. Unlike triggered abilities, state-based effects pay no attention to what happens during the resolution of a spell or ability.

Example: A player controls a creature with the ability "This creature's power and toughness are each equal to the number of cards in your hand" and plays a spell whose effect is "Discard your hand, then draw seven cards." The creature will temporarily have toughness 0 in the middle of the spell's resolution but will be back up to toughness 7 when the spell finishes resolving. Thus the creature will survive when state-based effects are checked. In contrast, an ability that triggers when the player has no cards in hand goes on the stack after the spell resolves, because its trigger event happened during resolution.

420.5. The state-based effects are as follows: 420.5a A player with 0 or less life loses the game.

420.5b A creature with toughness 0 or less is put into its owner's graveyard. Regeneration can't replace this event.

420.5c A creature with lethal damage, but greater than 0 toughness, is destroyed. Lethal damage is an amount of damage greater than or equal to a creature's toughness. Regeneration can replace this event.

420.5d An Aura attached to an illegal permanent or player, or not attached to a permanent or player, is put into its owner's graveyard.

420.5e If two or more legendary permanents with the same name are in play, all are put into their owners' graveyards. This is called the "legend rule." If only one of those permanents is legendary, this rule doesn't apply.

420.5f A token in a zone other than the in-play zone ceases to exist.

420.5g A player who attempted to draw a card from an empty library since the last time state-based effects were checked loses the game.

420.5h A player with ten or more poison counters loses the game.

420.5i If two or more permanents have the supertype world, all except the one that has been a permanent with the world supertype in play for the shortest amount of time are put into their owners' graveyards. In the event of a tie for the shortest amount of time, all are put into their owners' graveyards. This is called the "world rule."

420.5j A copy of a spell in a zone other than the stack ceases to exist. A copy of a card in any zone other than the stack or the in-play zone ceases to exist.

420.5k An Equipment attached to an illegal permanent becomes unattached from that permanent but remains in play.

420.5m A non-Aura, non-Equipment permanent attached to another permanent becomes unattached from that permanent but remains in play.

420.5n If a permanent has both a +1/+1 counter and a -1/-1 counter on it, N +1/+1 and N -1/-1 counters are removed from it, where N is the smaller of the number of +1/+1 and -1/-1 counters on it.

421. Handling "Infinite" Loops

421.1. Occasionally the game can get into a state in which a set of actions could be repeated forever. These rules (sometimes called the "infinity rules") govern how to break such loops.

421.2. If the loop contains one or more optional actions and one player controls them all, that player chooses a number. The loop is treated as repeating that many times or until another player intervenes, whichever comes first.

421.3. If a loop contains optional actions controlled by two players and actions by both of those players are required to continue the loop, the first player (or the first involved player after the active player in turn order) chooses a number. The other player then has two choices. He or she can choose a lower number, in which case the loop continues that number of times plus whatever fraction is necessary for the active player to "have the last word." Or he or she can agree to the number the first player chose, in which case the loop continues that number of times plus whatever fraction is necessary for the second player to "have the last word." (Note that either fraction may be zero.) This sequence of choices is extended to all applicable players if there are more than two players involved.

Example: In a two-player game, one player controls a creature with the ability "{0}: [This creature] gains flying," and another player controls a permanent with the ability "{0}: Target creature loses flying." The "infinity rule" ensures that regardless of which player initiated the gain/lose flying ability, the nonactive player will always have the final choice and therefore be able to determine whether the creature has flying. (Note that this a.s.sumes that the first player attempted to give the creature flying at least once.) 421.4. If the loop contains only mandatory actions, the game ends in a draw. (See rule 102.4b.) 421.5. If the loop contains optional actions controlled by different players and these actions don't depend on one another, the active player chooses a number. In APNAP order, the nonactive players can each either agree to that number or choose a higher number. Note that this rule applies even if the actions could exist in separate loops rather than in a single loop.

422. Handling Illegal Actions

422.1. If a player realizes that he or she can't legally take an action after starting to do so, the entire action is reversed and any payments already made are canceled. No abilities trigger and no effects apply as a result of an undone action. If the action was playing a spell, the spell returns to the zone it came from. The player may also reverse any legal mana abilities played while making the illegal play, unless mana from them or from any triggered mana abilities they triggered was spent on another mana ability that wasn't reversed. Players may not reverse actions that moved cards to a library or from a library to any zone other than the stack.

422.2. When reversing illegal spells and abilities, the player who had priority retains it and may take another action or pa.s.s. The player may redo the reversed action in a legal way or take any other action allowed by the rules.

423. Drawing a Card

423.1. A player draws a card by putting the top card of his or her library into his or her hand. This is done as a game action during each player's draw step. It may also be done as part of a cost or effect of a spell or ability.

423.2. Cards may only be drawn one at a time. If a player is instructed to draw multiple cards, that player performs that many individual card draws.

423.2a If an effect instructs more than one player to draw cards, the active player performs all of his or her draws first, then each other player in turn order does the same.

432.2b If an effect instructs more than one player to draw cards in a Two-Headed Giant game, first the primary player (seated on the right) on the active team performs all of his or her draws, then the secondary player on that team performs all of his or her draws, then the nonactive team does the same.

423.3. If there are no cards in a player's library and an effect offers that player the choice to draw a card, that player may choose to do so. See rule 413.2c.

423.4. A player who attempts to draw a card from an empty library loses the game the next time a player would receive priority. (This is a state-based effect. See rule 420.5g.) 423.5. If an effect moves cards from a player's library to that player's hand without using the word "draw," the player has not drawn those cards. This makes a difference for abilities that trigger on drawing cards or that replace card draws, as well as if the player's library is empty.

423.6. Some effects replace card draws.

423.6a An effect that replaces a card draw is applied even if no cards could be drawn because there are no cards in the affected player's library.

423.6b If an effect replaces a draw within a sequence of card draws, the replacement effect is completed before resuming the sequence.

423.6c Some effects perform additional actions on a card after it's drawn. If the draw is replaced, the additional action is not performed on any cards that are drawn as a result of that replacement effect or any subsequent replacement effects.

5. Additional Rules

500. Legal Attacks and Blocks

500.1. 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.

500.2. 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 has 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 may 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.

500.3. 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 has 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 to block.) 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.

500.5. When determining what requirements could be obeyed without violating restrictions, you don't need to consider any options for a creature that don't satisfy a requirement on it. But you do need to consider any options for any creature(s) that will satisfy a requirement, as long as the total number of obeyed requirements is increased (even if the option means not obeying another requirement that was previously met).

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." The creature with no abilities isn't required to block. It's legal to declare both creatures as blockers, or to declare neither creature as a blocker, but illegal to block with only one of the two.

501. Evasion Abilities

501.1. Evasion abilities restrict what can block an attacking creature. These are static abilities that modify the declare blockers step of the combat phase.

501.2. Evasion abilities are c.u.mulative.

Example: A creature with flying and shadow can't be blocked by a creature with flying but without shadow.

501.3. Some creatures have abilities that restrict how they can block. As with evasion abilities, these modify only the rules for 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.) 502. Keyword Abilities 502.1. Most abilities describe exactly what they do in the card's rules text. Some, though, are very common or would require too much s.p.a.ce to define on the card. In these cases, the object lists only the name of the ability as a "keyword"; sometimes reminder text summarizes the game rule.

502.2. First Strike

502.2a First strike is a static ability that modifies the rules for the combat damage step. (See rule 310, "Combat Damage Step.") 502.2b At the start of the combat damage step, if at least one attacking or blocking creature has first strike or double strike (see rule 502.28), creatures without first strike or double strike don't a.s.sign combat damage. Instead of proceeding to end of combat, the phase gets a second combat damage step to handle the remaining creatures. In the second combat damage step, surviving attackers and blockers that didn't a.s.sign combat damage in the first step, plus any creatures with double strike, a.s.sign their combat damage.

502.2c Adding or removing first strike after the first combat damage step won't prevent a creature from dealing combat damage or allow it to deal combat damage twice.

502.2d Multiple instances of first strike on the same creature are redundant.

502.3. Flanking 502.3a Flanking is a triggered ability that triggers during the declare blockers step. (See rule 309, "Declare Blockers Step.") "Flanking" means "Whenever this creature becomes blocked by a creature without flanking, the blocking creature gets -1/-1 until end of turn."

502.3b If a creature has multiple instances of flanking, each triggers separately.

502.4. Flying 502.4a Flying is an evasion ability.

502.4b A creature with flying can't be blocked by creatures without flying. A creature with flying can block a creature with or without flying. (See rule 309, "Declare Blockers Step.") 502.4c Multiple instances of flying on the same creature are redundant.

502.5. Haste 502.5a Haste is a static ability.

502.5b A creature with haste can attack or use activated abilities whose cost includes the tap symbol even if it hasn't been controlled by its controller continuously since the beginning of his or her most recent turn. (See rule 212.3d.) 502.5c Multiple instances of haste on the same creature are redundant.

502.6. Landwalk 502.6a Landwalk and snow landwalk are generic terms; a card's rules text will give a specific subtype or supertype (such as in "islandwalk," "snow swampwalk," or "legendary landwalk").

502.6b Landwalk and snow landwalk are evasion abilities. A creature with landwalk is unblockable as long as the defending player controls at least one land with the specified subtype and/or supertype. (See rule 309, "Declare Blockers Step.") 502.6c Snow landwalk is a special type of landwalk. A creature with snow landwalk is unblockable as long as the defending player controls at least one snow land with the specified subtype. If a player is allowed to choose any landwalk ability, that player may choose a snow landwalk ability. If an effect causes a permanent to lose all landwalk abilities, snow landwalk abilities are removed as well.

502.6d Landwalk or snow landwalk abilities don't "cancel" one another.

Example: If a player controls a snow Forest, that player can't block an attacking creature with snow forestwalk even if he or she also controls a creature with snow forestwalk.

502.6e Multiple instances of the same type of landwalk or snow landwalk on the same creature are redundant.

502.7. Protection 502.7a Protection is a static ability, written "Protection from [quality]." This quality is usually a color (as in "protection from black") but can be any characteristic value. If the quality is a type, subtype, or supertype, the protection applies to sources that are permanents with that type, subtype, or supertype and to any sources not in play that are of that type, subtype, or supertype.

502.7b A permanent with protection can't be targeted by spells with the stated quality and can't be targeted by abilities from a source with the stated quality.

502.7c A permanent with protection can't be enchanted by Auras that have the stated quality. Such Auras attached to the permanent with protection will be put into their owners' graveyards as a state-based effect. (See rule 420, "State-Based Effects.") 502.7d A permanent with protection can't be equipped by Equipment that have the stated quality. Such Equipment become unattached from that permanent, but remain in play. (See rule 420, "State-Based Effects.") 502.7e Any damage that would be dealt by sources that have the stated quality to a permanent that has protection is prevented.

502.7f If a creature with protection attacks, it can't be blocked by creatures that have the stated quality.

502.7g Multiple instances of protection from the same quality on the same permanent are redundant.

502.8. Shadow 502.8a Shadow is an evasion ability.

502.8b A creature with shadow can't be blocked by creatures without shadow, and a creature without shadow can't be blocked by creatures with shadow. (See rule 309, "Declare Blockers Step.") 502.8c Multiple instances of shadow on the same creature are redundant.

502.9. Trample 502.9a Trample is a static ability that modifies the rules for a.s.signing an attacking creature's combat damage. A creature with trample has no special abilities when blocking or dealing noncombat damage. (See rule 310, "Combat Damage Step.") 502.9b The controller of an attacking creature with trample first a.s.signs damage to the creature(s) blocking it. If all those blocking creatures are a.s.signed lethal damage, any remaining damage is a.s.signed as its controller chooses among those blocking creatures and the defending player. When checking for a.s.signed lethal damage, take into account damage already on the creature and damage from other creatures that will be a.s.signed at the same time (see rule 502.9e). The controller need not a.s.sign lethal damage to all those blocking creatures but in that case can't a.s.sign any damage to the defending player.

502.9c If all the creatures blocking an attacking creature with trample are removed from combat before the combat damage step, all its damage is a.s.signed to the defending player.

502.9d a.s.signing damage from a creature with trample considers only the actual toughness of a blocking creature, not any abilities or effects that might change the final amount of damage dealt.