Fan Casting Mongul in Supergirl: Woman Of Tomorrow

At the end of the story, after Kara finishes her mission and her adventure, she manages to rebuild her ship which will take him to the planet where his cousin Kal El is supposed to be, but in that, a flash would take him to an unknown planet, which would be used as a prisoner for a fighting stadium, being Mongul the dictator who managed to capture her, the rest is history in Superman: Wardworld.