418.5c An effect is said to “depend on” another if (a) it’s applied in the same layer (and, if applicable, sublayer) as the other effect (see rule 418.5a) and (b) applying the other would change the text or the existence of the first effect, what it applies to, or what it does to any of the things it applies to. Otherwise, the effect is considered to be independent of the other effect.
418.5d An effect dependent on one or more other effects waits to apply until just after all of those effects have been applied, even if this causes a characteristic-setting ability to apply after another effect. If multiple dependent effects would apply simultaneously in this way, they’re applied in “timestamp order” relative to each other. If several dependent effects form a dependency loop, then this rule is ignored and the effects in the dependency loop are applied in timestamp order.
418.5e An object’s timestamp is the time it entered the zone it’s currently in, with three exceptions: (a) If two or more objects enter a zone (or zones) simultaneously, the active player determines their timestamp order at the time they enter that zone. (b) Whenever an Aura or Equipment becomes attached to a permanent, the Aura or Equipment receives a new timestamp. (c) Permanents that phase in keep the same timestamps they had when they phased out.
418.5f A continuous effect generated by a static ability has the same timestamp as the object the static ability is on, or the timestamp of the effect that created the ability, whichever is later.
418.5g A continuous effect generated by the resolution of a spell or ability receives a timestamp at the time it’s created.
418.5h One continuous effect can override another. Sometimes the results of one effect determine whether another effect applies or what another effect does.
Example: Two Auras are played on the same creature: “Enchanted creature gains flying” and “Enchanted creature loses flying.” Neither of these depends on the other, since nothing changes what they affect or what they’re doing to it. Applying them in timestamp order means the one that was generated last “wins.” It’s irrelevant whether an effect is temporary (such as “Target creature loses flying until end of turn”) or global (such as “All creatures lose flying”).
Example: One effect reads, “White creatures get +1/+1,” and another, “Enchanted creature is white.” The enchanted creature gets +1/+1 from the first effect, regardless of its previous color.
418.5i Some effects switch a creature’s power and toughness. When they’re applied, they take the value of power and apply it to the object’s toughness, and take the object’s toughness and apply it to the object’s power. These effects are applied after all other effects that affect power and toughness. (See rule 418.5a.)
Example: A 1/3 creature is given +0/+1 by an effect. Then another effect switches the creature’s power and toughness. Its new power and toughness is 4/1. A new effect gives the creature +5/+0. Its “unswitched” power and toughness would be 6/4, so its actual power and toughness is 4/6.
Example: A 1/3 creature is given +0/+1 by an effect. Then another effect switches the creature’s power and toughness. Its new power and toughness is 4/1. If the +0/+1 effect ends before the switch effect ends, the creature becomes a 3/1.
418.6. Text-Changing Effects
418.6a An effect that changes the text of an object changes only those words that are used in the correct way (for example, a Magic color word being used as a color word, a land type word used as a land type, or a creature type word used as a creature type). The effect can’t change a proper noun, such as a card name, even if that proper noun contains a word or a series of letters that is the same as a Magic color word, basic land type, or creature type.
418.6b Effects that add or remove abilities don’t change the text of the objects they affect, so any abilities that are granted to an object can’t be changed by effects that change the text of that object.
418.6c Spells and abilities that create creature tokens use creature types to define both the creature types and the names of the tokens. These words can be changed, because they are being used as creature types, even though they’re also being used as names.
418.6d A creature token’s creature type and rules text are defined by the spell or ability that created the token. These characteristics can be changed by text-changing effects.
419. Replacement and Prevention Effects
419.1. Replacement and prevention effects are continuous effects that watch for a particular event to happen and then completely or partially replace that event. These effects act like “shields” around whatever they’re affecting.
419.1a Effects that use the word “instead” are replacement effects. Most replacement effects use the word “instead” to indicate what events will be replaced with other events and use the word “skip” to indicate what events, steps, phases, or turns will be replaced with nothing.
419.1b Effects that read “[This permanent] comes into play with . . . ,” “As [this permanent] comes into play . . . ,” or “[This permanent] comes into play as . . . ” are replacement effects.
419.1c Continuous effects that read “[This permanent] comes into play . . .” or “[Objects] come into play . . .” are replacement effects.
419.1d Effects that use the word “prevent” are prevention effects. Prevention effects use “prevent” to indicate what events will not occur.
419.1e Effects that read “As [this permanent] is turned face up . . . ,” are replacement effects.
419.2. Replacement and prevention effects apply continuously as events happen-they aren’t locked in ahead of time.
419.3. There are no special restrictions on playing a spell or ability that generates a replacement or prevention effect. Such effects last until they’re used up or their duration has expired.
419.4. Replacement or prevention effects must exist before the appropriate event occurs-they can’t “go back in time” and change something that’s already happened. Usually spells and abilities that generate these effects are played in response to whatever would produce the event and thus resolve before that event would occur.
Example: A player can play a regeneration ability in response to a spell that would destroy a creature he or she controls.
419.5. If an event is prevented or replaced, it never happens. A modified event occurs instead, which may in turn trigger abilities. Note that the modified event may contain instructions that can’t be carried out, in which case the player simply ignores the impossible instruction.
419.5a If a source would deal 0 damage, it does not deal damage at all. That means abilities that trigger on damage being dealt won’t trigger. It also means that replacement effects that increase damage dealt have no event to replace, so they have no effect.
419.5b Some abilities read, “you may [X]. If you do, [Y].” An “if you do” clause that follows a “you may [X]” clause refers to choosing to do the event X, regardless of what events actually occur as a result of that decision. If X is replaced entirely or in part by a different event, the “if you do” clause refers to the event that replaced X.
419.6. Replacement Effects
419.6a A replacement effect doesn’t invoke itself repeatedly and gets only one opportunity for each event.
Example: A player controls two permanents, each with an ability that reads “If a creature you control would deal damage to a creature or player, it deals double that damage to that creature or player instead.” A creature that normally deals 2 damage will deal 8 damage-not just 4, and not an infinite amount.
419.6b Regeneration is a destruction-replacement effect. The word “instead” doesn’t appear on the card but is implicit in the definition of regeneration. “Regenerate [permanent]” means “The next time [permanent] would be destroyed this turn, instead remove all damage from it, tap it, and (if it’s in combat) remove it from combat.” Abilities that trigger from damage being dealt still trigger even if the permanent regenerates.
419.6c Some effects replace damage dealt to one creature or player with
the same damage dealt to another creature or player; such effects are called “redirection” effects. If either creature is no longer in play or is no longer a creature when the damage would be redirected, the effect does nothing.
419.6d Some spells and abilities replace part or all of their own effect(s) when they resolve. Such effects are called self-replacement effects. When applying replacement effects to an event, apply self-replacement effects first, then apply other replacement effects.
419.6e Skipping an action, step, phase, or turn is a replacement effect. “Skip [something]” is the same as “Instead of doing [something], do nothing.” Once a step, phase, or turn has started, it can no longer be skipped-any skip effects will wait until the next occurrence.
419.6f Anything scheduled for a skipped step, phase, or turn won’t happen. Anything scheduled for the “next” occurrence of something waits for the first occurrence that isn’t skipped. If two effects each cause a player to skip his or her next occurrence, that player must skip the next two; one effect will be satisfied in skipping the first occurrence, while the other will remain until another occurrence can be skipped.
419.6g Some replacement effects say “instead choose one -.” Such effects are called modal replacement effects. The mode is chosen as the replacement effect is applied. If a modal replacement effect would apply to multiple events, a different mode may be chosen for each event. A modal replacement effect doesn’t invoke itself repeatedly, regardless of which mode was chosen. You may not choose modes that are impossible.
419.6h Some effects replace card draws. These effects are applied even if no cards could be drawn because there are no cards in the affected player's library. If an effect replaces a draw within a sequence of card draws, all actions required by the replacement are completed, if possible, before resuming the sequence. If an effect would have a player both draw a card and perform an additional action on that card, and the draw is replaced, the additional action is not performed on any cards that are drawn as a result of that replacement effect.
419.7. Prevention Effects
419.7a Prevention effects usually apply to damage that would be dealt.
419.7b Some prevention effects refer to a specific amount of damage-for example, “Prevent the next 3 damage that would be dealt to target creature or player this turn.” These work like shields. Each 1 damage that would be dealt to the “shielded” creature or player is prevented. Preventing 1 damage reduces the remaining shield by 1. If damage would be dealt to the shielded creature or player by two or more sources at the same time, the player or the controller of the creature chooses which damage the shield prevents first. Once the shield has been reduced to 0, any remaining damage is dealt normally. Such effects count only the amount of damage; the number of events or sources dealing it doesn’t matter.
419.7c Some prevention effects prevent the next N damage that would be dealt to each of a number of untargeted creatures. Such an effect creates a prevention shield for each applicable creature when the spell or ability that generates that effect resolves.
Example: Wojek Apothecary has an ability that says “{T}: Prevent the next 1 damage that would be dealt to target creature and each other creature that shares a color with it this turn.” When the ability resolves, it gives the target creature and each other creature in play that shares a color with it at that time a shield preventing the next 1 damage that would be dealt to it. Changing creatures’ colors after the ability resolves doesn’t add or remove shields, and creatures that come into play later in the turn don’t get the shield.
419.8. Sources of Damage
419.8a Some effects apply to damage from a source-for example, “The next time a red source of your choice would deal damage to you this turn, prevent that damage.” If an effect requires a player to choose a source, he or she may choose a permanent, a spell on the stack (including an artifact, creature, or enchantment spell), or any card or permanent referred to by an object on the stack (including a creature that assigned combat damage on the stack, even if the creature is no longer in play or is no longer a creature). The source is chosen when the effect is created. If the player chooses a permanent, the prevention will apply to the next damage from that permanent, regardless of whether it’s from one of that permanent’s abilities or combat damage dealt by it. If the player chooses an artifact, creature, or enchantment spell, the prevention will apply to any damage from that spell and from the permanent that it becomes when it resolves.
419.8b Some effects from spells and abilities prevent or replace damage from sources with certain properties, such as a creature or a source of a particular color. When the source would deal damage, the “shield” rechecks the source’s properties. If the properties no longer match, the damage isn’t prevented or replaced. If for any reason the shield prevents no damage or replaces no damage, the shield isn’t used up.
419.8c Some effects from static abilities prevent or replace damage from sources with certain properties. For these effects, the prevention or replacement applies to sources that are permanents with that property and to any sources that aren’t in play that have that property.
419.9. Interaction of Replacement or Prevention Effects
419.9a If two or more replacement or prevention effects are attempting to modify the way an event affects an object or player, the affected object’s controller (or its owner if it has no controller) or the affected player chooses one to apply. Then the other effect applies if it is still appropriate. If one or more of the applicable replacement effects is a self-replacement effect (see rule 419.6d), that effect is applied before any other replacement effects. If two or more players have to make these choices at the same time, choices are made in APNAP order (see rule 103.4).
Example: Two permanents are in play. One is an enchantment that reads “If a card would be put into a graveyard, instead remove it from the game,” and the other is a creature that reads “If [this creature] would be put into a graveyard from play, instead shuffle it into its owner’s library.” The controller of the creature that would be destroyed decides which replacement to apply first; the other does nothing.
419.9b A replacement effect can become applicable to an event as the result of another replacement effect that modifies the event.
Example: One effect reads “For each 1 life you would gain, instead draw a card,” and another reads “If you would draw a card, return a card from your graveyard to your hand instead.” Both effects combine (regardless of the order they came into existence): Instead of gaining 1 life, the player puts a card from his or her graveyard into his or her hand.
420. State-Based Effects
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 c
hecked. 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.
Magic: The Gathering Comprehensive Rules Page 9