You haven't activated an exhaust ability this turn if
Avatar Kuruk's ability has been activated previously.
Mana Needed
({20} magic symbol) minus ({1} magic symbol) for each creature and artifact you control each turn available.
Steps
Activate
Avatar Kuruk by paying ({20} magic symbol) minus ({1} magic symbol) for each creature and/or artifact you can tap while activating it, causing you to take an extra turn after this one.
Repeat each turn.
Notes
Because of
Elvish Refueler, you can continually activate
Avatar Kuruk's ability despite normally not being able to. You must make sure not to activate any other exhaust abilities before activating