600.4a.

When a player leaves the game, all objects (see rule 200.8) owned by that player leave the game, all spells and abilities controlled by that player on the stack cease to exist, and any change-of-control effects which give that player control of any objects end. Then, if there are any objects still controlled by that player, those objects leave the game. (Any objects leaving the game this way that aren't owned by the player leaving the game are placed in the removed-from-the-game zone.) This is not a state-based effect. It happens as soon as the player leaves the game. A player leaving the game doesn't affect combat damage on the stack.

Example: Alex plays Control Magic, an Aura that reads, "You control enchanted creature," on Bianca's Wall of Wood. If Alex leaves the game, so does Control Magic, and Wall of Wood reverts to Bianca's control. If, instead, Bianca leaves the game, so does Wall of Wood, and Control Magic is put into Alex's graveyard.

Example: Alex plays Threaten, which reads, in part, "Untap target creature and gain control of it until end of turn," targeting Bianca's Wall of Wood. If Alex leaves the game, Threaten's change-of-control effect ends and Wall of Wood reverts to Bianca's control.

Example: Alex plays Bribery, which reads, "Search target opponent's library for a creature card and put that card into play under your control. Then that player shuffles his or her library," targeting Bianca. Alex puts Wall of Wood into play from Bianca's library. If Alex leaves the game, Wall of Wood leaves the game. If, instead, Bianca leaves the game, Wall of Wood still leaves the game.

Example: Alex controls Genesis Chamber, which reads, "Whenever a nontoken creature comes into play, if Genesis Chamber is untapped, that creature's controller puts a 1/1 Myr artifact creature token into play." If Alex leaves the game, all Myr tokens created by Genesis Chamber while it was under Alex's control leave the game as well because Alex owns the tokens.