185.4. For Abilities , they are the Ability’s Controller.
185.4.a. By default, the Controller of an Ability’s Source is the Controller of that Ability.
185.4.b. Changes to Control of an Ability’s Source do not change Control of that Ability.
185.4.c. That player chooses targets.
185.4.d. That player chooses modes.
185.4.e. That player pays costs.