- Talk to Amos, and the entire party will be teleported down where Geist Balrog Phase 1 awaits - which takes the form of Jr. Balrog.
- Defeat that, then Geist Balrog Phase 2 will spawn in its place - which takes the form of Crimson Balrog. Kill it.
- Finally, Geist Balrog Phase 3 will appear. It is obviously the hardest among the 3 phases, and is capable of powerful attacks which includes random teleportation, physical or magical invincibility, can cast Dispel, and has a scratching attack.
- Kill it to get the Geist Fang, then give it to Amos. You will then be brought to the Bonus stage.