What is the converted mana cost of a spell with {X} when cast with the Miracle mechanic?

Say I topdeck Entreat the Angels and cast it for its miracle cost of XWW. But my opponent wants to counter it with a CMC-based effect, such as Spellstutter Sprite or Spell Burst.

202.3. The converted mana cost of an object is a number equal to the total amount of mana in its mana cost, regardless of color....

202.3b When calculating the converted mana cost of an object with {X} in its mana cost, X is treated as 0 while the object is not on the stack, and X is treated as the number chosen for it while the object is on the stack.

If I spent 5 mana to cast Entreat the Angels with X=3, what is the CMC of Entreat the Angels on the stack?

Do I get to double-count the X I spent because the card's base mana cost is XXWWW?

Or is X "zero" because I'm not actually paying the X in the mana cost?

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3 Answers

The CMC is 9.

The XX in the mana cost and the X in the alternative cost are related. In your example, you chose X = 3, so the Converted Mana Cost (CMC) becomes 3+3+3 = 9. You only pay 3WW, but spells asking for the CMC of a spell, permanent, or card don't care about what you actually pay/have paid, they only care about what's printed in the upper right corner (usually) of a card.

How to calculate the CMC:

202.1. A card’s mana cost is indicated by mana symbols near the top of the card. (See rule 107.4.) On most cards, these symbols are printed in the upper right corner. Some cards from the Future Sight set have alternate frames in which the mana symbols appear to the left of the illustration.

202.3. The converted mana cost of an object is a number equal to the total amount of mana in its mana cost, regardless of color.

202.3b When calculating the converted mana cost of an object with {X} in its mana cost, X is treated as 0 while the object is not on the stack, and X is treated as the number chosen for it while the object is on the stack.

Spells don't care about alternative costs:

117.9c. An alternative cost doesn't change a spell's mana cost, only what its controller has to pay to cast it. Spells and abilities that ask for that spell's mana cost still see the original value.

The X in the alternative costs is the same X as those in the mana costs:

107.3g All instances of X on an object have the same value at any given time.

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Isn't that covered by

117.9c. An alternative cost doesn't change a spell's mana cost, only what its controller has to pay to cast it. Spells and abilities that ask for that spell's mana cost still see the original value.

?

So while your Entreat's on the stack, its CMC would be 9 (since CMC is based on the mana cost).

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I clarified the question slightly. – Alex P May 9 '12 at 1:54
@AlexP The rules you yourself cite are clear that the cmc of spells on the stack includes all X mana used to cast it. Seems to me just because you're using an alternate cost to reduce the CMC obviously doesn't change the actual CMC seen by the countering card. Basically you're defining the cmc as 9, but "chosing" to cast it for 5 as an alternative cost. – Circeus May 9 '12 at 5:12
@Circeus He doesn't define the CMC as 9. The XX in the mana costs and the X in the alternative costs are completely unrelated. – Hackworth May 9 '12 at 7:20
I see where you're coming from, Circeus, in that it seems "fair" for the X in the Miracle cost to be somehow connected the X in the mana cost. But unless this was explicitly stated in the rules somewhere, we aren't allowed to assume it; and I'm pretty sure that it would be too complicated and fiddly for Wizards to make a rule out of anyway. – thesunneversets May 9 '12 at 9:14
Circeus, I'm giving you a +1 for this answer too, in recognition of your intuitions being right long before the rest of us got there! – thesunneversets May 15 '12 at 11:19

This was bugging me sufficiently that I asked it as a question on the MTG-RULES mailing list, and received the following response (which fortunately confirms the above answers!):

The converted mana cost is 9.

The idea is that you choose X before you determine how much mana you pay. You don't say "cast it for 3WW" then attempt to determine the value of X, but rather decide on a value for X, announce you're using the Miracle alternate cost, and only then determine that, e.g., it costs 3WW for X = 3.

X has indeed the same value on every instance on a card, and has the value chosen for it when it's on the stack. If you chose X = 3, then the converted mana cost is 9 on the stack.

So, to paraphrase it in a way that helps me understand, "the X" of a spell is essentially a feature of a spell that you declare as you announce that spell, in much the same way as its target, or the mode of a modal spell. It's not so much part of the mana cost, as something the mana cost is later derived from!

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