If a player is instructed to search a hidden zone for cards that match an undefined quality, that player may still search that zone but can’t find any cards.
July 3, 2020 · Core Set 2021
Each clashing player reveals the top card of their library at the same time. Then those players decide in APNAP order (see rule 101.4) where to put those cards, then those cards move at the same time.
May 3, 2019 · War of the Spark
A player may planeswalk as the result of the “planeswalking ability” (see rule 901.8), because the owner of a face-up plane card or phenomenon card leaves the game (see rule 901.10), or because a phenomenon’s triggered ability leaves the stack (see rule 704.5x). Abilities may also instruct a player to planeswalk.
January 25, 2019 · Ravnica Allegiance
A player may planeswalk as the result of the "planeswalking ability" (see rule 901.8), because the owner of a face-up plane card or phenomenon card leaves the game (see rule 901.10), or because a phenomenon's triggered ability leaves the stack (see rule 704.5x). Abilities may also instruct a player to planeswalk.
April 27, 2018 · Dominaria
A player may planeswalk as the result of the “planeswalking ability” (see rule 901.8), because the owner of a face-up plane card or phenomenon card leaves the game (see rule 901.10), or because a phenomenon’s triggered ability leaves the stack (see rule 704.5x). Abilities may also instruct a player to planeswalk.
September 30, 2016 · Kaladesh
Schemes may only be set in motion one at a time. If a player is instructed to set multiple schemes in motion, that player sets a scheme in motion that many times.
September 30, 2011 · Innistrad
rule 701.23c not present in this release
June 17, 2011 · Commander 2011
To proliferate in a Two-Headed Giant game means to choose any number of permanents
April 1, 2011 · Duel Decks: Knights vs. Dragons
To proliferate in a Two-Headed Giant game means to choose any number of permanents and/or teams that have a counter, then give each exactly one additional counter of a kind that permanent or team already has. See rule 810, "Two-Headed Giant Variant."