If an object requires a player who has left the game to pay a cost or choose whether to pay a cost, that cost is not paid.
February 1, 2012 · Dark Ascension
If an object requires a player who has left the game to make a choice, 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.
September 30, 2011 · Innistrad
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.
June 17, 2011 · Commander 2011
If an effect requires information about a specific player, the effect uses the current
February 4, 2011 · Mirrodin Besieged
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.
October 1, 2010 · Scars of Mirrodin
If an effect requires information about a specific player, the effect uses the current
February 1, 2010 · Worldwake
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.