From the Comprehensive Rules (Amonkhet (April 28, 2017))
- 608. Resolving Spells and Abilities
- 608.1. Each time all players pass in succession, the spell or ability on top of the stack resolves. (See rule 609, “Effects.”)
- 608.2. If the object that’s resolving is an instant spell, a sorcery spell, or an ability, its resolution may involve several steps. The steps described in rules 608.2a and 608.2b are followed first. The steps described in rules 608.2c–j are then followed as appropriate, in no specific order. The step described in rule 608.2k is followed last.
- 608.2a If a triggered ability has an intervening “if” clause, it checks whether the clause’s condition is true. If it isn’t, the ability is removed from the stack and does nothing. Otherwise, it continues to resolve. See rule 603.4.
- 608.2b If the spell or ability specifies targets, it checks whether the targets are still legal. A target that’s no longer in the zone it was in when it was targeted is illegal. Other changes to the game state may cause a target to no longer be legal; for example, its characteristics may have changed or an effect may have changed the text of the spell. If the source of an ability has left the zone it was in, its last known information is used during this process. The spell or ability is countered if all its targets, for every instance of the word “target,” are now illegal. If the spell or ability is not countered, it will resolve normally. Illegal targets, if any, won’t be affected by parts of a resolving spell’s effect for which they’re illegal. Other parts of the effect for which those targets are not illegal may still affect them. If the spell or ability creates any continuous effects that affect game rules (see rule 613.10), those effects don’t apply to illegal targets. If part of the effect requires information about an illegal target, it fails to determine any such information. Any part of the effect that requires that information won’t happen.
Example: Sorin’s Thirst is a black instant that reads, “Sorin’s Thirst deals 2 damage to target creature and you gain 2 life.” If the creature isn’t a legal target during the resolution of Sorin’s Thirst (say, if the creature has gained protection from black or left the battlefield), then Sorin’s Thirst is countered. Its controller doesn’t gain any life.
Example: Plague Spores reads, “Destroy target nonblack creature and target land. They can’t be regenerated.” Suppose the same animated land is chosen both as the nonblack creature and as the land, and the color of the creature land is changed to black before Plague Spores resolves. Plagues Spores isn’t countered because the black creature land is still a legal target for the “target land” part of the spell. The “destroy target nonblack creature” part of the spell won’t affect that permanent, but the “destroy target land” part of the spell will still destroy it. It can’t be regenerated.
- 608.2c The controller of the spell or ability follows its instructions in the order written. However, replacement effects may modify these actions. In some cases, later text on the card may modify the meaning of earlier text (for example, “Destroy target creature. It can’t be regenerated” or “Counter target spell. If that spell is countered this way, put it on top of its owner’s library instead of into its owner’s graveyard.”) Don’t just apply effects step by step without thinking in these cases—read the whole text and apply the rules of English to the text.
- 608.2d If an effect of a spell or ability offers any choices other than choices already made as part of casting the spell, activating the ability, or otherwise putting the spell or ability on the stack, the player announces these while applying the effect. The player can’t choose an option that’s illegal or impossible, with the exception that having a library with no cards in it doesn’t make drawing a card an impossible action (see rule 120.3). If an effect divides or distributes something, such as damage or counters, as a player chooses among any number of untargeted players and/or objects, the player chooses the amount and division such that at least one player or object is chosen if able, and each chosen player or object receives at least one of whatever is being divided. (Note that if an effect divides or distributes something, such as damage or counters, as a player chooses among some number of target objects and/or players, the amount and division were determined as the spell or ability was put onto the stack rather than at this time; see rule 601.2d.)
Example: A spell’s instruction reads, “You may sacrifice a creature. If you don’t, you lose 4 life.” A player who controls no creatures can’t choose the sacrifice option.
- 608.2e Some spells and abilities have multiple steps or actions, denoted by separate sentences or clauses, that involve multiple players. In these cases, the choices for the first action are made in APNAP order, and then the first action is processed simultaneously. Then the choices for the second action are made in APNAP order, and then that action is processed simultaneously, and so on. See rule 101.4.
- 608.2f If an effect gives a player the option to pay mana, he or she may activate mana abilities before taking that action. If an effect specifically instructs or allows a player to cast a spell during resolution, he or she does so by following the steps in rules 601.2a–i, except no player receives priority after it’s cast. That spell becomes the topmost object on the stack, and the currently resolving spell or ability continues to resolve, which may include casting other spells this way. No other spells can normally be cast and no other abilities can normally be activated during resolution.
- 608.2g If an effect requires information from the game (such as the number of creatures on the battlefield), the answer is determined only once, when the effect is applied. If the effect requires information from a specific object, including the source of the ability itself, the effect uses the current information of that object if it’s in the public zone it was expected to be in; if it’s no longer in that zone, or if the effect has moved it from a public zone to a hidden zone, the effect uses the object’s last known information. See rule 112.7a. If an ability states that an object does something, it’s the object as it exists—or as it most recently existed—that does it, not the ability.
- 608.2h If an effect refers to certain characteristics, it checks only for the value of the specified characteristics, regardless of any related ones an object may also have.
Example: An effect that reads “Destroy all black creatures” destroys a white-and-black creature, but one that reads “Destroy all nonblack creatures” doesn’t.
- 608.2i If an ability’s effect refers to a specific untargeted object that has been previously referred to by that ability’s cost or trigger condition, it still affects that object even if the object has changed characteristics.
Example: Wall of Tears says “Whenever Wall of Tears blocks a creature, return that creature to its owner’s hand at end of combat.” If Wall of Tears blocks a creature, then that creature ceases to be a creature before the triggered ability resolves, the permanent will still be returned to its owner’s hand.
- 608.2j If an instant spell, sorcery spell, or ability that can legally resolve leaves the stack once it starts to resolve, it will continue to resolve fully.
- 608.2k As the final part of an instant or sorcery spell’s resolution, the spell is put into its owner’s graveyard. As the final part of an ability’s resolution, the ability is removed from the stack and ceases to exist.
- 608.3. If the object that’s resolving is a permanent spell, its resolution involves a single step (unless it’s an Aura). The spell card becomes a permanent and is put onto the battlefield under the control of the spell’s controller.
- 608.3a If the object that’s resolving is an Aura spell, its resolution involves two steps. First, it checks whether the target specified by its enchant ability is still legal, as described in rule 608.2b. (See rule 702.5, “Enchant.”) If so, the spell card becomes a permanent and is put onto the battlefield under the control of the spell’s controller attached to the object it was targeting.
- 608.3b If a permanent spell resolves but its controller can’t put it onto the battlefield, that player puts it into its owner’s graveyard.
Example: Worms of the Earth has the ability “Lands can’t enter the battlefield.” Clone says “You may have Clone enter the battlefield as a copy of any creature on the battlefield.” If a player casts Clone and chooses to copy Dryad Arbor (a land creature) while Worms of the Earth is on the battlefield, Clone can’t enter the battlefield from the stack. It’s put into its owner’s graveyard.