X

For the Core Set, see 10th Edition.

On a card X can mean two different things:

• In the casting cost, is a variable mana cost of a spell.
• In a text box it means a variable, such as "Gain X life" or "Deal X damage" which is usually based on the in the mana cost of the spell.

Rulings

• If a spell or ability has a cost with an “” in it, the value of X must be announced as part of playing the spell or ability. (See rule 409, “Playing Spells and Activated Abilities.”) While the spell or ability is on the stack, the in its mana cost equals the amount announced as part of playing the spell or ability. If a card in any other zone has in its mana cost, the amount is treated as 0. If you’re playing a spell that has in its mana cost and an effect lets you play it without paying any cost that includes , the only legal choice for is 0. This does not apply to effects that only reduce a cost, even if they reduce it to zero. See rule 409, “Playing Spells and Activated Abilities.”
• If a cost associated with a special action, such as a suspend cost or a morph cost, has an “” in it, the value of is chosen by the player taking the special action as he or she pays that cost.
• In triggered abilities, X is defined when the ability resolves. It may be defined by the text of the ability, by a keyword ability of the card, or by the trigger event. See rule 410, “Handling Triggered Abilities.”
• In other cases, X is defined by the text of a spell or ability. If X isn’t defined, the controller of the spell or ability chooses the value of X. All Xs on an object have the same value.

Trivia

• Shifting Wall is the first card to ever have a mana cost of just .
• The mana cost symbols and (with the same function as ) are obsolete. has been used on the black-bordered Fireball , was only used the silver-bordered The Ultimate Nightmare of Wizards of the Coast® Customer Service

See also and Numbers and symbols