The Final Coil of Bahamut

Determined to stop Bahamut's regeneration and free Louisoix Leveilleur from his enthrallment to the Dreadwyrm, Alisaie Leveilleur and the Warrior of Light try to enter the remaining interment hulks. As both the vessels in the Burning Wall and the Singing Shards are blocked by crystal formations, they must utilize Dalamud's Talons as a back door to enter the remaining fragments. This time, they are accompanied by Alphinaud Leveilleur.

At the Central Decks, they discover the key mechanism of Bahamut's continued summoning: numerous Meracydians bound in stasis to eternally summon the Dreadwyrm, and not, as Alisaie thought, by artificially simulating prayers itself. Realizing the extent of Allagan ingenuity and cruelty, they conclude that disabling the regeneration should allow them to perish. They next discover the Regeneration Grid, a smaller scale replica of Dalamud itself. Alisaie realizes Bahamut must have spent millennia gazing at this unchanging view, in a prison that could scarcely contain him.

At the Main Bridge, they are confronted by Louisoix, who attempts to stop them from deactivating the internment hulk's regeneration function. He explains the origins of Bahamut: a fallen great wyrm of the ancient first brood, whom the dragons of Meracydia summoned as a primal in their hour of need against the Allagan invasion five thousand years ago, only for the deity to end up bound by their imperial adversaries. As Louisoix had summoned the Twelve during the Battle of Carteneau, he asks why the Meracydians should be condemned while he exalted. Speaking the sentiments of the Dreadwyrm, Louisoix states that dragons will never know peace as long as man remains. Alisaie rebukes his words, declaring her grandfather would never shake his faith in mankind and the common people.

Undeterred, Louisoix notes even his grandchildren's inability to understand the other's reasonings, despite clinging to the banner of the "salvation of Eorzea". Alphinaud, while not dismissing his words about him and his sister, finds his tirade against mankind dubious. He asks his grandfather if his sudden views are because he is enthralled by Bahamut, or because he has transcended the limitations of man's existence. Louisoix confirms Alphinaud's suspicions, by revealing his primal form: the Phoenix. Once the primal of rebirth is defeated, Bahamut relinquishes his hold on Louisoix, who regains his former senses.

Thanking the Warrior of Light for freeing his mind, he takes time to explain what happened after the Battle of Carteneau. The cloud of aether from the failed summoning of the Twelve to contain Bahamut's fury had coalesced within him, and with the prayers of himself and Eorzeans, infused him with the power of a primal. He used his divine power to shatter Bahamut's form, ending the rampage before any more of the realm could be destroyed and attempted to relinquish aether back to the land. Bahamut's will would not perish, and seized his essence and dragged him underground with the primal's heart. Most of the aether had returned to the land, so Bahamut could not fully restore his form. Instead, the automated fragments of Dalamud sought to rebuild the Dreadwyrm, having tunneled underground to locate his remains. He then disables the third internment hulk, and creates a portal to the final hold to disable the regeneration. He spends his final moments having a heart-to-heart with his grandchildren before fading.

Now with their task clear, they proceed to the final interment hulk to deactivate Bahamut's regeneration. The Dreadwyrm's wrath would not be so easily contained, and Bahamut attempts to halt the shutdown himself with a Gigaflare. Using their twin grimoires, Alisaie and Alphinaud hold back the primal's power while the Warrior of Light enters the Burning Heart to confront the primal's essence. Only upon its defeat can the final internment hulk be turned off, disabling the regeneration of the Dreadwyrm, and allowing the primal to dissipate completely. With their task done, Alphinaud and Alisaie swear to keep what transpired a secret for fear of Eorzeans attempting to summon their grandfather as a primal.

Returning to Northern Thanalan, they meet with Urianger Augurelt, who agrees to help them keep the truth of the calamity confidential and allow the matter to rest and the realm move on. Back at the Burning Wall, Alisaie and the Warrior of Light look over the fallen Ragnarok and parts of the crystallized remains of Bahamut. She leaves a bouquet of flowers in memory of Louisoix, Nael, and the dragons of Meracydian before informing the adventure she plans to go on a journey across the realm to find her new path.