Rule 191.5.a

By default, the Controller of an Ability’s Source is the Controller of that Ability.

• 191.5.a.1 If an Ability’s Source is located in a non-Board Zone, the Ability’s Controller is the Owner of the Source.
• 191.5.a.2 If an Ability allows players other than the Controller or Owner of its Source to play it, the player that plays the…

Official Core Rules