381. All Activated Abilities can only be activated on the appropriate Player's Turn and during an Open State.
381.1. If the source of the Activated Ability is controlled by a player, that is the controller's Main Phase during an Open State.
381.2. If the source of the Activated Ability is uncontrolled and it isn't a Battlefield, that is the owner's Main Phase during an Open State.
381.3. If the Activated Ability specifies that one or more players other than the controller or owner of the source can activate it, that is during the activating player's Main Phase during an Open State.