Rethink

Instant, 2U (3)
Counter target spell unless its controller pays {X}, where X is its converted mana cost.
"Are you sure you want to do that?"
Illus. Matt Cavotta

Crystal Keep Rulings Summaries

• The spell's controller gets the option to pay when this spell resolves. [Prophecy FAQ 2000/05/25]
• Note - Also see Converted Mana Cost, Rule G3.29.

Format Legality	Legal in Vintage, Legacy Banned in Extended, Standard
Printings (1/6)	Prophecy (Common)