The Lord of Nightmares requests Kami-Sama to help stabilize her universe. She creates a powerful crystal that will elevate a person to godhood. Ranma is training to use magic, when he feels something. He looks, and finds the Senshi fighting a metal creature. He cant fight it, so he draws in power, unfortunately he cant shut off the draw. Kami-Sama notices and decides to give Ranma the crystal. Once elevated, Ranma is summoned to the other universe along with the Senshi by Lina Inverse. Ranma and the Senshi have a long adventure to save the world before returning. The Senshi become Ranma’s priestesses. (Ah! My Goddess, Sailor Moon, Slayers Crossover.)