Supergirl and the Cinder Games - Laurie S. Sutton - Bog

A prisoner on the planet Apokolips, her memory of her powers suppressed, Supergirl has been reduced to a serving girl for Granny Goodness and the Female Furies; but when she watches trainees prepare for the Cinder Games something in their moves is familiar, and with the help of a Mother Box she enters the games in disguise and wins, recovers her true identity, and escapes through a portal, leaving only a boot behind.