Progress through the main story until you reach the endgame area
Enter the Astral Prism during the final sequence
Speak with Emperor and reach the point where Orpheus is revealed
Obtain the Orphic Hammer from Raphael
Refuse Emperor’s plan to keep Orpheus imprisoned
Use the Orphic Hammer on Orpheus’s chains
Choose to free Orpheus when prompted
Be prepared to fight the Emperor after freeing Orpheus
Continue with Orpheus as your ally for the final battle