In a Planechase game, a face-up plane or phenomenon card is controlled by the player designated as the planar controller. This is usually the active player. See rule 901.6.
July 3, 2020 · Core Set 2021
In a Vanguard game, each vanguard card is controlled by its owner. See rule 902.6.
February 1, 2012 · Dark Ascension
In an Archenemy game, each scheme card is controlled by its owner. See rule 904.7.