Puca's Mischief | Magic: The Gathering
Formats Puca's Mischief is Legal in
Official Oracle Text for Puca's Mischief
Official Rulings for Puca's Mischief
5/1/2008 : Even if you don't plan on exchanging control of any permanents, if you can choose two legal targets when the ability triggers, you must do so. If you can't, then you don't choose any targets.
5/1/2008 : If either one of the targets becomes illegal (because it leaves the battlefield or for any other reason) by the time the ability resolves, the exchange won't happen. If both targets become illegal, the ability is countered.