Isochron Scepter reads, in part,

You may copy the exiled card. If you do, you may cast the copy without paying its mana cost.

There are a number of other cards that give you the option of copying a card, and then give you the option of casting that copy.

Effectively, each of these cards offers three options:

  1. Don't copy the card.
  2. Copy the card, but don't cast the copy.
  3. Copy the card and cast the copy.

Why would I ever choose option 2? Is there ever a situation where choosing option 2 results in a different game state than if I had chosen option 1?

My perception is that WoTC usually tries very hard to avoid redundancy in card text, so I'm curious why they would choose a wording like this over something like,

You may copy the exiled card and cast the copy without paying its mana cost.

Edit: and in fact now that I look at the images of the original Mirrodin block printings, the cards did originally have only one instance of "may" in the instructions for casting the copy. So by issuing this errata, WoTC very deliberately wants there to be two opportunities to make a choice. But why?

  • Not an answer, but you can think about the timing of when these choices are made. ie: you tap scepter to put ability on stack, opp responds with something, when scepter ability resolves you decide you don't actually want to cast the thing after all. – Malco Aug 7 at 14:21
  • I agree that there are times when you would prefer not to copy the card and cast the copy. For instance, you might not want to cast an imprinted Doom Blade if your opponent sacrifices his only creature in response to your activation. But in that case, you can simply choose option #1 and never copy Doom Blade to begin with. – Kevin Aug 7 at 14:26
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    Interesting that Spellbinder as printed (as opposed to Oracle wording), does not have the second "may". So it was given errata for that at some point. – GendoIkari Aug 7 at 14:50
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    Well spotted. Googling "Spellbinder errata", I see, which says "The text has been clarified to indicate that each action is an optional choice. [...] There is no functional change in the way these cards are played". So this confirms that WoTC definitely wants there to be separate optional choices, but it doesn't give much indication of why that is important. – Kevin Aug 7 at 14:56
  • The only indication I can see is "if the spell can't be legally played", which was already on my mind before I saw that. As worded now; if the spell can't be legally played, then you aren't allowed to choose to play it after copying it due to the "can't make illegal choice" rule. Under the old wording, if the spell can't be legally played, you could choose to copy it, but if you did it would fail to do be cast as part of "does as much as possible". So a different rule ends up being applied (to the same ultimate effect). – GendoIkari Aug 7 at 15:01
up vote 6 down vote accepted

You may copy the exiled card and cast the copy without paying its mana cost.

That wording is ambiguous[1]. Fixed:

You may copy the exiled card. If you do, cast the copy without paying its mana cost.

This is bad. Casting the copy might become illegal during casting. In that case, one would have to roll back the casting and choose to do something else instead. But because casting the copy is mandatory, and because casting a spell that becomes illegal to cast is not illegal itself, that's not possible. The game would enter into an undefined state, at least in theory. Making the casting optional avoids this issue.

But what about

Copy the exiled card. You may cast the copy without paying its mana cost.

While that would be equivalent given the cards that current exist[2], I think people would find that weirder and/or more confusing than two "may".

  1. See Hackworth's answer for details.
  2. See Hackworth's answer for details.
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    If casting were illegal, wouldn’t it just fall under “if an effect attempts to do something impossible, it does as much as possible”? – GendoIkari Aug 8 at 13:35
  • Now this is an interesting idea. But what's stopping the game from rewinding even farther back, to the "you may copy..." choice? 721.1 discusses reversing illegal actions. What constitutes an "action"? Since it's not in the glossary, one might be expected to use whatever plain English definition that makes the most sense in context. I'd be inclined to use the definition that doesn't lead to an undefined game state. – Kevin Aug 8 at 13:43
  • @Kevin What stops the game from rewinding even further back? "601.2 [...] If, at any point during the casting of a spell, a player is unable to comply with any of the steps listed below, the casting of the spell is illegal; the game returns to the moment before the casting of that spell was proposed [...]." – Rainbolt Aug 8 at 13:53
  • @GendoIkari, Casting a spell that will become illegal to cast is not illegal, so doing as much as possible requires that you cast the spell. That's why casting spells can be rolled back, and that's why "may" is used. – ikegami Aug 8 at 19:24
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    @Gendolkari, Nothing stops you. There's a good question related to this which I'll dig up for you once my cat gets off of me so I can use my computer. – ikegami Aug 8 at 19:34

Warning: Clicking on the first link will download a .doc file.

From A Summary of Recent Rulings published by the Magic Rules Team in February 2005:


  • Isochron Scepter and Similar Cards

The Mirrodin(R) block contains a group of cards that create copies of cards and allow a player to play those copies. The creation of the copy and then the playing of the copy are both optional. The text has been clarified to indicate that each action is an optional choice. If the spell can't be legally played, choosing not to use either option is acceptable. There is no functional change in the way these cards are played. The new Oracle text for the cards is as follows:


As spelled out here, the errata was not a functional change, which means that despite how the printed text may be interpreted today, each action has always been optional.

Why would I ever choose option 2? Is there ever a situation where choosing option 2 results in a different game state than if I had chosen option 1?

At the time this answer was written, option 1 and option 2 are identical. However, if a card were printed tomorrow with the text...

Whenever you copy a card, you gain 1 life.

... then suddenly the two options would be different.

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    Regarding your hypothetical at the end, the cards in question do not actually copy spells; they copy cards, then cast the copies. – murgatroid99 Aug 7 at 16:01
  • @murgatroid99 Thanks, corrected. – Rainbolt Aug 7 at 16:19

In practice, there is no difference between not copying the card and not playing the copy, because there are no cards or interactions that care about either. In theory, "game state" is an official, yet ill-defined term and at the moment, there is no correct rules-based answer whether or not the different options could have different effects on the game state.

A copy of a card is created in the same zone the original is in:

706.12. An effect that instructs a player to cast a copy of an object (and not just copy a spell) follows the rules for casting spells, except that the copy is created in the same zone the object is in and then cast while another spell or ability is resolving. Casting a copy of an object follows steps 601.2a–h of rule 601, “Casting Spells,” and then the copy becomes cast. Once cast, the copy is a spell on the stack, and just like any other spell it can resolve or be countered.

If you choose to copy a card but don't cast it, it ceases to exist as a state-based action the next time a player would get priority:

704.5e If a copy of a spell is in a zone other than the stack, it ceases to exist. If a copy of a card is in any zone other than the stack or the battlefield, it ceases to exist.

Since to my knowledge there are no effects that care about a copy of a card, or any object for that matter, ceasing to exist, there is no practical difference between not copying a card and not casting the copy.

As for effects on game state: The term is used loosely in the CR. It is used 16 times throughout the current rules, but is never clearly defined - it doesn't even have an entry in the glossary, even though state-based triggers depend on it:

603.8. Some triggered abilities trigger when a game state (such as a player controlling no permanents of a particular card type) is true, rather than triggering when an event occurs. These abilities trigger as soon as the game state matches the condition. [..]

The shortcut rules come closest to defining game state as "anything that happens in the game that some ability or effect might care about", which isn't all too helpful, because the definition is essentially circular: the game state determines what the game state is.

720.3. Sometimes a loop can be fragmented, meaning that each player involved in the loop performs an independent action that results in the same game state being reached multiple times. [..]

Example: In a two-player game, the active player controls a creature with the ability “{0}: [This creature] gains flying,” the nonactive player controls a permanent with the ability “{0}: Target creature loses flying,” and nothing in the game cares how many times an ability has been activated. Say the active player activates his creature’s ability, it resolves, then the nonactive player activates her permanent’s ability targeting that creature, and it resolves. This returns the game to a game state it was at before. [..]

In the loop example, activating the two abilities once each is game state neutral. However, if something else was in the game that cared about the activations, the activations would not be neutral. Especially in a game with hidden information, having an ill-defined game state is unfortunate, to say the least.

The point is, going by the example of 720.3, creating a copy of a card and not casting it is the same as not creating a copy of a card, because nothing cares about either of the two options. But there is no rules reference to say for sure either way.

As for your wording: I do not find it equivalent to the current wording. I take it you mean to say that

You may (copy the exiled card and cast the copy without paying its mana cost.)

However, a player could also understand

(You may copy the exiled card) and (cast the copy without paying its mana cost.)

There is potential for confusion, since a player could rightly ask how to cast the copy if I declined to create it? The current wording leaves no room for interpretation and reduces player confusion, which is good design outside of the mechanical details.

As for rules interactions, combining the two instructions of copying and playing the card is equivalent to the current wording of two separate decisions. However, if anything in the future ever cared about copying cards and/or letting them cease to exist by not casting them, all cards with your proposed wording would require errata, or rather, could have unintended interactions such as being required to cast a spell just in order to get a copy first, if all you want is a copy.

  • I agree that there is potential for confusion with my proposed wording (and by extension, the wording as it appears on the card). But if WoTC were only interested in clarifying that the casting is dependent on the copying, I might expect the errata to be "You may copy the exiled card. If you do, cast the copy without paying its mana cost." I also agree that there could one day be a card that cares about copies of cards. But this seems like an unusually narrow design space to worry about when choosing wording for existing cards. – Kevin Aug 7 at 17:36
  • Just to be clear; it's not possible to cast the copy using mana if you decline to do it for free? It's an exiled card at that point, right? – JollyJoker Aug 8 at 11:12
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    @JollyJoker Correct. Cards like Isochron Scepter give you a one time option to cast a card from exile. You must accept or decline during resolution. There is no "I'll choose later." option. On the other hand, continuous effects from cards like Outpost Siege allow you to cast a card from exile until the end of your turn. – Rainbolt Aug 8 at 14:06

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