Some spells, activated abilities, and triggered abilities read, "[Do something]. If [a player] [does or doesn't], [effect]." or "[A player] may [do something]. If [that player] [does or doesn't], [effect]." The action [do something] is a cost, paid when the spell or ability resolves. The "If [a player] [does or doesn't]" clause checks whether the player chose to pay an optional cost or started to pay a mandatory cost, regardless of what events actually occurred.

Example: You control Standstill, an enchantment that says "When a player casts a spell, sacrifice Standstill. If you do, each of that player's opponents draws three cards." A spell is cast, causing Standstill's ability to trigger. Then an ability is activated that exiles Standstill. When Standstill's ability resolves, you're unable to pay the "sacrifice Standstill" cost. No player will draw cards.

Example: Your opponent has cast Gather Specimens, a spell that says "If a creature would enter the battlefield under an opponent's control this turn, it enters the battlefield under your control instead." You control a face-down Dermoplasm, a creature with morph that says "When Dermoplasm is turned face up, you may put a creature card with morph from your hand onto the battlefield face up. If you do, return Dermoplasm to its owner's hand." You turn Dermoplasm face up, and you choose to put a creature card with morph from your hand onto the battlefield. Due to Gather Specimens, it enters the battlefield under your opponent's control instead of yours. However, since you chose to pay the cost, Dermoplasm is still returned to its owner's hand.

Some spells, activated abilities, and triggered abilities read, "[Do something]. If [a player] [does, doesn't, or can't], [effect]." or "[A player] may [do something]. If [that player] [does, doesn't, or can't], [effect]." The action [do something] is a cost, paid when the spell or ability resolves. The "If [a player] [does, doesn't, or can't]" clause checks whether the player chose to pay an optional cost or started to pay a mandatory cost, regardless of what events actually occurred.

Example: You control Standstill, an enchantment that says "When a player casts a spell, sacrifice Standstill. If you do, each of that player's opponents draws three cards." A spell is cast, causing Standstill's ability to trigger. Then an ability is activated that exiles Standstill. When Standstill's ability resolves, you're unable to pay the "sacrifice Standstill" cost. No player will draw cards.

Example: Your opponent has cast Gather Specimens, a spell that says "If a creature would enter the battlefield under an opponent's control this turn, it enters the battlefield under your control instead." You control a face-down Dermoplasm, a creature with morph that says "When Dermoplasm is turned face up, you may put a creature card with morph from your hand onto the battlefield face up. If you do, return Dermoplasm to its owner's hand." You turn Dermoplasm face up, and you choose to put a creature card with morph from your hand onto the battlefield. Due to Gather Specimens, it enters the battlefield under your opponent's control instead of yours. However, since you chose to pay the cost, Dermoplasm is still returned to its owner's hand.

If an effect says that a player can't gain life, that player can't make an exchange such that the player's life total would become higher; in that case, the exchange won't happen. In addition, a cost that involves having that player gain life can't be paid, and a replacement effect that would replace a life gain event affecting that player won't do anything.

If an effect says that a player can't gain life, that player can't make an exchange such that the player's life total would become higher; in that case, the exchange won't happen. Similarly, if an effect redistributes life totals, a player can't receive a new life total such that the player's life total would become higher. In addition, a cost that involves having that player gain life can't be paid, and a replacement effect that would replace a life gain event affecting that player won't do anything.

If an effect says that a player can't lose life, that player can't make an exchange such that the player's life total would become lower; in that case, the exchange won't happen. In addition, a cost that involves having that player pay life can't be paid.

If an effect says that a player can't lose life, that player can't make an exchange such that the player's life total would become lower; in that case, the exchange won't happen. Similarly, if an effect redistributes life totals, a player can't receive a new life total such that the player's life total would become lower. In addition, a cost that involves having that player pay life can't be paid.

An ability word appears in italics at the beginning of some abilities. Ability words are similar to keywords in that they tie together cards that have similar functionality, but they have no special rules meaning and no individual entries in the Comprehensive Rules. The ability words are battalion, bloodrush, channel, chroma, cohort, constellation, converge, council's dilemma, delirium, domain, fateful hour, ferocious, formidable, grandeur, hellbent, heroic, imprint, inspired, join forces, kinship, landfall, lieutenant, metalcraft, morbid, parley, radiance, raid, rally, spell mastery, strive, sweep, tempting offer, threshold, and will of the council.

An ability word appears in italics at the beginning of some abilities. Ability words are similar to keywords in that they tie together cards that have similar functionality, but they have no special rules meaning and no individual entries in the Comprehensive Rules. The ability words are battalion, bloodrush, channel, chroma, cohort, constellation, converge, council's dilemma, delirium, domain, fateful hour, ferocious, formidable, grandeur, hellbent, heroic, imprint, inspired, join forces, kinship, landfall, lieutenant, metalcraft, morbid, parley, radiance, raid, rally, revolt, spell mastery, strive, sweep, tempting offer, threshold, and will of the council.

If an object would move from one zone to another, determine what event is moving the object. If the object is moving to a public zone and its owner will be able to look at it in that zone, its owner looks at it to see if it has any abilities that would affect the move. If the object is moving to the battlefield, each other player who will be able to look at it in that zone does so. Then any appropriate replacement effects, whether they come from that object or from elsewhere, are applied to that event. If any effects or rules try to do two or more contradictory or mutually exclusive things to a particular object, that object's controller—or its owner if it has no controller—chooses which effect to apply, and what that effect does. (Note that multiple instances of the same thing may be mutually exclusive; for example, two simultaneous "destroy" effects.) Then the event moves the object.

If an object would move from one zone to another, determine what event is moving the object. If the object is moving to a public zone and its owner will be able to look at it in that zone, its owner looks at it to see if it has any abilities that would affect the move. If the object is moving to the battlefield, each other player who will be able to look at it in that zone does so. Then any appropriate replacement effects, whether they come from that object or from elsewhere, are applied to that event. If any effects or rules try to do two or more contradictory or mutually exclusive things to a particular object, that object's controller—or its owner if it has no controller—chooses which effect to apply, and what that effect does. (Note that multiple instances of the same thing may be mutually exclusive; for example, two simultaneous "destroy" effects.) Then the event moves the object.

Example: Exquisite Archangel has an ability which reads "If you would lose the game, instead exile Exquisite Archangel and your life total becomes equal to your starting life total." A spell deals 5 damage to a player with 5 life and 5 damage to an Exquisite Archangel under that player's control. As state-based actions are performed, that player's life total becomes equal to his or her starting life total, and that player chooses whether Exquisite Archangel moves to its owner's graveyard or to exile.

Delayed triggered abilities come from spells or other abilities that create them on resolution, or are created as the result of a replacement effect being applied. That means a delayed triggered ability won't trigger until it has actually been created, even if its trigger event occurred just beforehand. Other events that happen earlier may make the trigger event impossible.

Example: Part of an effect reads "When this creature leaves the battlefield," but the creature in question leaves the battlefield before the spell or ability creating the effect resolves. In this case, the delayed ability never triggers.

Example: If an effect reads "When this creature becomes untapped" and the named creature becomes untapped before the effect resolves, the ability waits for the next time that creature untaps.

Delayed triggered abilities are created during the resolution of spells or abilities, as the result of a replacement effect being applied, or as a result of a static ability that allows a player to take an action. A delayed triggered ability won't trigger until it has actually been created, even if its trigger event occurred just beforehand. Other events that happen earlier may make the trigger event impossible.

Example: Part of an effect reads "When this creature leaves the battlefield," but the creature in question leaves the battlefield before the spell or ability creating the effect resolves. In this case, the delayed ability never triggers.

Example: If an effect reads "When this creature becomes untapped" and the named creature becomes untapped before the effect resolves, the ability waits for the next time that creature untaps.

When life totals are exchanged, each player gains or loses the amount of life necessary to equal the other player's previous life total. Replacement effects may modify these gains and losses, and triggered abilities may trigger on them.

When life totals are exchanged, each player gains or loses the amount of life necessary to equal the other player's previous life total. Replacement effects may modify these gains and losses, and triggered abilities may trigger on them. A player who can't gain life can't be given a higher life total this way, and a player who can't lose life can't be given a lower life total this way (see rules 118.7-8).

A spell or ability may instruct a player to exchange two numerical values. In such an exchange, each value becomes equal to the previous value of the other. If either of those values is a life total, the affected player gains or loses the amount of life necessary to equal the other value. Replacement effects may modify this gain or loss, and triggered abilities may trigger on it. If either of those values is a power or toughness, a continuous effect is created setting that power or toughness to the other value (see rule 613.3b). This rule does not apply to spells and abilities that switch a creature's power and toughness.

A spell or ability may instruct a player to exchange two numerical values. In such an exchange, each value becomes equal to the previous value of the other. If either of those values is a life total, the affected player gains or loses the amount of life necessary to equal the other value. Replacement effects may modify this gain or loss, and triggered abilities may trigger on it. A player who can't gain life can't be given a higher life total this way, and a player who can't lose life can't be given a lower life total this way (see rules 118.7-8). If either of those values is a power or toughness, a continuous effect is created setting that power or toughness to the other value (see rule 613.3b). This rule does not apply to spells and abilities that switch a creature's power and toughness.

A creature with toughness greater than 0 that's been dealt damage by a source with deathtouch since the last time state-based actions were checked is destroyed as a state-based action. See rule 704.

A creature with toughness greater than 0 that's been dealt damage by a source with deathtouch since the last time state-based actions were checked is destroyed as a state-based action. See rule 704.

Any nonzero amount of combat damage assigned to a creature by a source with deathtouch is considered to be lethal damage, regardless of that creature's toughness. See rules 510.1c-d.

Any nonzero amount of combat damage assigned to a creature by a source with deathtouch is considered to be lethal damage for the purposes of determining if a proposed combat damage assignment is valid, regardless of that creature's toughness. See rules 510.1c-d.

Convoke is a static ability that functions while the spell with convoke is on the stack. "Convoke" means "For each colored mana in this spell's total cost, you may tap an untapped creature of that color you control rather than pay that mana. For each generic mana in this spell's total cost, you may tap an untapped creature you control rather than pay that mana." The convoke ability isn't an additional or alternative cost and applies only after the total cost of the spell with convoke is determined.

Example: Heartless Summoning says, in part, "Creature spells you cast cost {2} less to cast." You control Heartless Summoning and cast Siege Wurm, a spell with convoke that costs {5}{G}{G}. The total cost to cast Siege Wurm is {3}{G}{G}. After activating mana abilities, you pay that total cost. You may tap up to two green creatures and up to three creatures of any color to pay that cost, and the remainder is paid with mana.

Convoke is a static ability that functions while the spell with convoke is on the stack. "Convoke" means "For each colored mana in this spell's total cost, you may tap an untapped creature of that color you control rather than pay that mana. For each generic mana in this spell's total cost, you may tap an untapped creature you control rather than pay that mana."

Multiple instances of convoke on the same spell are redundant.

Multiple instances of convoke on the same spell are redundant.

Delve is a static ability that functions while the spell with delve is on the stack. "Delve" means "For each generic mana in this spell's total cost, you may exile a card from your graveyard rather than pay that mana." The delve ability isn't an additional or alternative cost and applies only after the total cost of the spell with delve is determined.

Delve is a static ability that functions while the spell with delve is on the stack. "Delve" means "For each generic mana in this spell's total cost, you may exile a card from your graveyard rather than pay that mana."

Multiple instances of delve on the same spell are redundant.

Multiple instances of delve on the same spell are redundant.