Modal

Modal describes a spell or ability. A modal spell or ability begins with "Choose one —" followed by multiple possible effect choices, or modes. When a modal spell or ability is announced its controller first chooses one of the modes to take effect before choosing its target or targets if it requires any.

There are two variations of modal spells and abilities: "An opponent chooses one —" appears on three spells, Fatal Lore, Library of Lat-Nam and Misfortune, all from the Alliances expansion. The other variation is called a modal replacement effect and reads "If [event], instead choose one —". This type of modal ability is found only on Time Vault.

From the Comprehensive Rules:

• Modal, Mode: A spell or ability is modal if it is written "choose one —" or "[a specified player] chooses one —." Modal spells and abilities offer a choice of effects. A modal spell or ability's controller must choose the mode as part of playing the spell or ability or as part of putting the ability on the stack (in the case of triggered abilities); see rule 409.1b. A modal replacement effect's mode is chosen as it's applied; see rule 419.6g.
• 409.1b If the spell or ability is modal (uses the phrase "Choose one —" or "[specified player] chooses one —"), the player announces the mode choice. If the player wishes to splice any cards onto the spell, he or she reveals those cards in his or her hand. If the spell or ability has a variable mana cost (indicated by {X}) or some other variable cost, the player announces the value of that variable at this time. If the spell or ability has alternative, additional, or other special costs (such as buyback, kicker, or convoke costs), the player announces his or her intentions to pay any or all of those costs (see rule 409.1f). You can't apply two alternative methods of playing or two alternative costs to a single spell or ability. Previously made choices (such as choosing to play a spell with flashback from his or her graveyard or choosing to play a creature with morph face down) may restrict the player's options when making these choices.
• 415.7b Modal spells and abilities may have different targeting requirements for each mode. Changing a spell or ability's target can't change its mode.
• 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.

See also entwine.