({1} magic symbol) plus an additional ({20} magic symbol) minus ({1} magic symbol) for each creature and artifact you control each turn available available.
Steps
Activate
Volrath by paying ({1} magic symbol) , causing it to become a copy of
Avatar Kuruk until your next turn.
Activate
Volrath 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.