Flash

Flash is a keyword ability which allows cards to be played at any time you could play an Instant. Flash first appeared in the Time Spiral expansion. Although this ability existed before Time Spiral, this is the first time it was used a keyword. The earliest card with Flash is Aluren from Tempest. Older cards with this ability have received errata to give them Flash.

From the ()

Reminder text

The latest reminder text for flash reads "You may cast this spell any time you could cast an instant."