Defeat the four fiends to unlock each new dungeon. Each features random maps, exclusive items, and bosses from other Final Fantasy Games. Beating all four fiends before venturing into the dungeons is recommended.

Lifespring Grotto - Defeat Kraken. Located near the canal by Melmond.
Earthgift Shrine - Defeat Lich. Located near Temple of Chaos.
Hellfire Chasm - Defeat Marilith. Located in the Dragon Islands.
Whisperwind Cove - Defeat Tiamat. Located in the rivers near the Ice Cave.