Casting a Spell

"I cast X in response" is really a fixed sequence of steps (rule 601.2). The order decides many rules questions: targets are chosen BEFORE costs, mana abilities come BEFORE payment. Only once all steps are complete does the spell count as cast — and only then do "whenever a player casts …" triggers fire.

1. 1 Announce & Move to the Stack

   The spell is proposed and the card immediately moves from wherever it is (usually the hand) to the top of the stack. It stays there until the spell resolves, is countered, or the casting is reversed because a later step can't be completed.

   Rules: 601.2a Official rules text + Official rules text −

   601.2aTo propose the casting of a spell, a player first moves that card (or that copy of a card) from where it is to the stack. It becomes the topmost object on the stack. It has all the characteristics of the card (or the copy of a card) associated with it, and that player becomes its controller. Any continuous effects that modify the characteristics of the spell as you start casting it begin as it is put on the stack (see rule 611.2f). Any one-shot effects that cause the spell to gain abilities as you cast it apply as it is put on the stack (see rule 610.5). The spell remains on the stack until it resolves, it’s countered, or a rule or effect moves it elsewhere.

2. 2 Make Choices

   All casting choices are made now: modes (for modal spells), whether to use additional costs (e.g. kicker) or alternative costs (e.g. "without paying its mana cost"), the value of X, and color choices for hybrid or Phyrexian mana.

   Rules: 601.2b Official rules text + Official rules text −

   601.2bIf the spell is modal, the player announces the mode choice (see rule 700.2). If the player wishes to splice any cards onto the spell (see rule 702.47), they reveal those cards in their hand. If the spell has alternative or additional costs that will be paid as it’s being cast such as buyback or kicker costs (see rules 118.8 and 118.9), the player announces their intentions to pay any or all of those costs (see rule 601.2f). A player can’t apply two alternative methods of casting or two alternative costs to a single spell. If the spell has a variable cost that will be paid as it’s being cast (such as an in its mana cost; see rule 107.3), the player announces the value of that variable. If the value of that variable is defined in the text of the spell by a choice that player would make later in the announcement or resolution of the spell, that player makes that choice at this time instead of that later time. If a cost that will be paid as the spell is being cast includes hybrid mana symbols, the player announces the nonhybrid equivalent cost they intend to pay. If a cost that will be paid as the spell is being cast includes Phyrexian mana symbols, the player announces whether they intend to pay 2 life or a corresponding colored mana cost for each of those symbols. Previously made choices (such as choosing to cast a spell with flashback from a graveyard or choosing to cast a creature with morph face down) may restrict the player’s options when making these choices.

3. 3 Choose Targets

   All targets are chosen — each target must be legal at this point. Important: this happens BEFORE costs are paid. You can't pay first and then look; and your opponent already knows what's being targeted when they respond.

   Rules: 601.2c Official rules text + Official rules text −

   601.2cThe player announces their choice of an appropriate object or player for each target the spell requires. A spell may require some targets only if an alternative or additional cost (such as a kicker cost) or a particular mode was chosen for it; otherwise, the spell is cast as though it did not require those targets. Similarly, a spell may require alternative targets only if an alternative or additional cost was chosen for it. If the spell has a variable number of targets, the player announces how many targets they will choose before they announce those targets. In some cases, the number of targets will be defined by the spell’s text. Once the number of targets the spell has is determined, that number doesn’t change, even if the information used to determine the number of targets does. The same target can’t be chosen multiple times for any one instance of the word “target” on the spell. However, if the spell uses the word “target” in multiple places, the same object or player can be chosen once for each instance of the word “target” (as long as it fits the targeting criteria). If any effects say that an object or player must be chosen as a target, the player chooses targets so that they obey the maximum possible number of such effects without violating any rules or effects that say that an object or player can’t be chosen as a target. The chosen objects and/or players each become a target of that spell. (Any abilities that trigger when those objects and/or players become the target of a spell trigger at this point; they’ll wait to be put on the stack until the spell has finished being cast.)

4. 4 Announce Division

   If the spell divides or distributes something (e.g. "divide 3 damage as you choose"), the division is announced now — each chosen target must receive at least 1.

   Rules: 601.2d Official rules text + Official rules text −

   601.2dIf the spell requires the player to divide or distribute an effect (such as damage or counters) among one or more targets, the player announces the division. Each of these targets must receive at least one of whatever is being divided.

5. 5 Legality Check

   The game checks whether the proposed spell, with all choices made, can legally be cast at all. If not, the entire casting is reversed: the game returns to the moment immediately before the spell was proposed.

   Rules: 601.2e 733.1 Official rules text + Official rules text −

   601.2eThe game checks to see if the proposed spell can legally be cast. If the proposed spell is illegal, the game returns to the moment before the casting of that spell was proposed (see rule 733, “Handling Illegal Actions”).

   733.1If a player takes an illegal action or starts to take an action but can’t legally complete it, 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 casting a spell, the spell returns to the zone it came from. Each player may also reverse any legal mana abilities that player activated while making the illegal play, unless mana from those abilities or from any triggered mana abilities they caused to trigger was spent on another mana ability that wasn’t reversed. Players may not reverse actions that moved cards to a library, moved cards from a library to any zone other than the stack, caused a library to be shuffled, or caused cards from a library to be revealed.

6. 6 Determine the Total Cost

   The total cost is calculated: mana or alternative cost plus cost increases, minus cost reductions. After that it is "locked in" — effects that only appear during payment can no longer change it.

   Rules: 601.2f Official rules text + Official rules text −

   601.2fThe player determines the total cost of the spell. Usually this is just the mana cost. Some spells have additional or alternative costs. Some effects may increase or reduce the cost to pay, or may provide other alternative costs. Costs may include paying mana, tapping permanents, sacrificing permanents, discarding cards, and so on. The total cost is the mana cost or alternative cost (as determined in rule 601.2b), plus all additional costs and cost increases, and minus all cost reductions. If multiple cost reductions apply, the player may apply them in any order. If the mana component of the total cost is reduced to nothing by cost reduction effects, it is considered to be . It can’t be reduced to less than . Once the total cost is determined, any effects that directly affect the total cost are applied. Then the resulting total cost becomes “locked in.” If effects would change the total cost after this time, they have no effect.

7. 7 Activate Mana Abilities

   If mana has to be paid, the player may now activate mana abilities (tapping lands etc.). Mana abilities don't use the stack — nobody can respond to the tapping.

   Rules: 601.2g Official rules text + Official rules text −

   601.2gIf the total cost includes a mana payment, the player then has a chance to activate mana abilities (see rule 605, “Mana Abilities”). Mana abilities must be activated before costs are paid.

8. 8 Pay the Costs

   All costs are paid in any order (mana, life, sacrifices, tapping …). Partial payments can't be taken back: whatever happens during payment has happened.

   Rules: 601.2h Official rules text + Official rules text −

   601.2hThe player pays the total cost. First, they pay all costs that don’t involve random elements or moving objects from the library to a public zone, in any order. Then they pay all remaining costs in any order. Partial payments are not allowed. Unpayable costs can’t be paid.

9. 9 The Spell Is Cast

   Once all steps are complete, the spell counts as cast. NOW triggers that respond to casting fire ("magecraft", "whenever an opponent casts a spell …"). Then the casting player gets priority again — the spell doesn't resolve immediately; everyone may respond first.

   Rules: 601.2i Official rules text + Official rules text −

   601.2iOnce the steps described in 601.2a–h are completed, effects that modify the characteristics of the spell as it’s cast are applied, then the spell becomes cast. Any abilities that trigger when a spell is cast or put onto the stack trigger at this time. If the spell’s controller had priority before casting it, they get priority.