If an object requires a player who has left the game to make a choice other than whether to pay a cost, the controller of the object chooses another player to make that choice. If the original choice was to be made by an opponent of the controller of the object, that player chooses another opponent if possible.
June 5, 2017 · Commander Anthology
If a rule requires a player who has left the game to make a choice, the next player in turn order makes that choice.
February 1, 2012 · Dark Ascension
If an effect requires information about a specific player, the effect uses the current information about that player if he or she is still in the game; otherwise, the effect uses the last known information about that player before he or she left the game.
September 30, 2011 · Innistrad
If a player leaves the game during his or her turn, that turn continues to its completion without an active player. If the active player would receive priority, instead the next player in turn order receives priority, or the top object on the stack resolves, or the phase or step ends, whichever is appropriate.
June 17, 2011 · Commander 2011
If a player leaves the game during his or her turn, that turn continues to its completion
February 4, 2011 · Mirrodin Besieged
If a player leaves the game during his or her turn, that turn continues to its completion without an active player. If the active player would receive priority, instead the next player in turn order receives priority, or the top object on the stack resolves, or the phase or step ends, whichever is appropriate.
October 1, 2010 · Scars of Mirrodin
If a player leaves the game during his or her turn, that turn continues to its completion
February 1, 2010 · Worldwake
If a player leaves the game during his or her turn, that turn continues to its completion without an active player. If the active player would receive priority, instead the next player in turn order receives priority, or the top object on the stack resolves, or the phase or step ends, whichever is appropriate.