In the beginning of the sixth and final chapter, "Milky Way Wishes", Marx tells Kirby about how the Sun and Moon are fighting and that only the power of a giant mechanical creature called Nova can make them stop, sending Kirby on the adventure. Once Nova appears, Marx suddenly pushes Kirby out of the way and wishes for control over Pop Star. Explaining that he was the one who started the fight between the Sun and Moon in the first place, Marx then turns into a more powerful form of himself, which has fangs and strange yellow wings, before sending Nova on a collision course with Pop Star. As the Sun and Moon hold Nova back, Kirby rides a magical Starship into Nova and disables its heart, then defeats Marx and sends him crashing into Nova to destroy them both. In Kirby Super Star Ultra, pieces of Nova fuse with Marx's dead body and revives him as the more powerful Marx Soul (マルクソウル Marukusouru), the final boss of the new and most difficult subgame "The True Arena" with a new design and improved attacks.