This is a take on the time when Power Girl was revealed to be Atlantean, and not Kryptonian. DC Comics eliminated their multiverse and poor Kara was left with no origin since she couldn't be a parallel Earth version of Supergirl anymore. Thus she became a descendant of Arion the sorcerer. Nowadays, since the multiverse is back, Kara's gone right back to being Kryptonian. This piece is also an homage to Neal Adams' cover for Superman #233.