Historical Rules · 18 June 2021
Rule 704.5k
Official source text from the 18 June 2021 Rules release
If two or more permanents have the supertype world, all except the one that has had the world supertype for the shortest amount of time are put into their owners’ graveyards. In the event of a tie for the shortest amount of time, all are put into their owners’ graveyards. This is called the “world rule.”