The final battle against Heldalf is a grueling, multi-stage encounter that will push your party to its limits. He cycles through various elemental affinities, so you'll need to constantly adapt your Armatization and Seraph pairings. In his initial form, he has no specific weakness, but as the fight progresses, he will temporarily gain weaknesses to Fire, Water, Earth, and Wind. Pay close attention to his aura to determine his current weakness. Utilize all your characters' Artes, especially their Mystic Artes when the Blast Gauge is full. The final phase is a test of endurance and precise execution. Keep your HP high, manage your SC, and exploit every opening. Reward: Game completion, post-game content unlocked.
