Desperate Gambit

Instant, R (1)
Choose a source you control and flip a coin. If you win the flip, the next time that source would deal damage this turn, it deals double that damage instead. If you lose the flip, the next time it would deal damage this turn, prevent that damage.¹
Illus. Pete Venters

Gatherer Card Rulings [Nov 2009]

• 10/4/2004: The coin is flipped during resolution of this spell, so you know in advance what will happen when the source deals damage the next time.
• 4/1/2008: The chosen source may be a permanent, a spell on the stack, anything referred to by something on the stack (such as a Prodigal Pyromancer that’s left the battlefield while its ability is still on the stack), or a creature that’s left the battlefield while its combat damage is still on the stack.

Format Legality	Legal in Vintage, Legacy Banned in Extended, Standard, MTGO Classic
Printings (1/6)	Weatherlight (Uncommon)