Previously, the action of using an activated ability was referred to on cards as “playing” that ability. Cards that were printed with that text have received errata in the Oracle card reference so they now refer to “activating” that ability.
July 3, 2020 · Core Set 2021
rule 701.18e not present in this release
May 3, 2019 · War of the Spark
If the effect that contains the search instruction doesn’t also contain instructions to reveal the found card(s), then they’re not revealed.
January 25, 2019 · Ravnica Allegiance
If the effect that contains the search instruction doesn't also contain instructions to reveal the found card(s), then they're not revealed.
April 27, 2018 · Dominaria
If the effect that contains the search instruction doesn’t also contain instructions to reveal the found card(s), then they’re not revealed.
September 30, 2016 · Kaladesh
If an effect causes a player to shuffle a library containing zero or one cards, abilities that trigger when a library is shuffled will still trigger.