And lo, vile beasts did rise... Leaving naught in their wake but blood and ash. Sun scorches earth and boils seas... And our sins ascend unto the heavens— Three dooms to unmake all we were.
The Final Days (終末の災厄, Shūmatsu no Saiyaku?, lit. Final Calamity) is a phenomenon believed to bring about the "end of the world" in Final Fantasy XIV. The concept was introduced in Final Fantasy XIV: Shadowbringers and is more extensively explored in Final Fantasy XIV: Endwalker.
Before Final Fantasy XIV
Long ago, before the great sundering, there was but a single world—Etheirys. One day, from within the earth, a terrible cry issued forth, affecting a profound change in all manner of life. We were not exempt. Our creation magicks ran rampant, giving shape and form to thoughts of hopelessness and despair. At first, the phenomenon was limited to a single region. But quickly...so very quickly...it spread and engulfed the whole of the star.The Watcher
The original Final Days was an event instigated by the Meteia, creations of Hermes he had created in order to traverse the great expanse. They shared a collective consciousness to communicate with each other and Hermes wherever they went. He was interested to discover other sentient races in the universe and sent the Meteia to learn their reasons for living, keeping a lone Meteion at his side as a receiver for their reports. When the Meteia began to compile their final report, the Meteion remaining by Hermes was overwhelmed by her sisters' hivemind. The Meteia had only discovered dead worlds or worlds on the brink of death. Driven by Hermes's question and trying to find a singular answer for the meaning of life, the Meteia concluded that life leads only to death and despair, and resolved to deliver the lives on Etheirys to their deaths to end their meaningless suffering. They retreated to the edge of the universe and began to sing their song of oblivion that made use of dynamis infused with despair, resonating with those at the lowest point of their lives to cause a chain reaction that would result in extinction. Hermes used Kairos to erase the recent memories of all but two of the people who had witnessed Meteion's descent into despair, himself included, leaving the Amaurotines unprepared for the coming apocalypse.
The Convocation of Fourteen, led by Emet-Selch, deemed the phenomenon to be related by stagnated aether within the currents of Etheirys, causing it to rot. The Convocation believed the summoning of a vastly powerful primal attuned to darkness, Zodiark, would reinstate the aether flow. While the summoning required sacrificing half of Etheirys's populace, Zodiark restored the world with his existence, halting the Final Days.
After Zodiark's summoning, he tempered the Convocation, and the surviving ancients were consumed by a desperate need to restore the world to the state it was before the Final Days. Thus, the Convocation kept sacrificing to Zodiark to restore life on Etheirys. They chose to offer the newly-developed life forms to bring back those who had been lost in the Final Days. Venat, a former Convocation member, and the only ancient to know the true cause of the Final Days, disapproved of this and gathered a group of like-minded ancients to oppose the Convocation's desires. In an effort for mankind to be able to move forward and not dwell on a past now lost, she chose to become the primal Hydaelyn at the cost of her splinter group. She wanted to imprison Zodiark long enough so those in their future could find a permanent solution. Hydaelyn defeated Zodiark by sundering Him and the world, and the world split into the Source and its thirteen reflections. Hydaelyn knew Zodiark was essential for the star's survival, as his destruction would return the Final Days. Hydaelyn set up contingency plans to evacuate the Source's residents should the Final Days resume. She created the moon in the Source that contained Zodiark and his seal, that also act as a vessel for people of Etheirys to evacuate the star. She also created the Loporrits as the caretaker of said vessel. The sundering also reduced aether in mankind, so that they would be able to more easily interact with dynamis, and thus resist the song of oblivion.
Last night, the isle was rocked by tremors, and the earth itself cried out. Aloft, the heavens began to burn. From all about, unholy beasts—the likes of which we had never seen—came forth in fury and rage. ...No. To say they "came forth" would be...inexact. The people of Radz-at-Han themselves transformed into these baleful fiends.Ahewann
In the present day, after the Scions of the Seventh Dawn returned to Eorzea from the First to continue the war effort against the Garlean Empire, they encountered a rogue Ascian, Fandaniel, who told them about his intention of bringing the second Final Days upon the star. To achieve this, he used the corpse of the deceased Garlean emperor Varis zos Galvus to create the primal Anima to erect several spires throughout the world to gather aether and transmit it to the Tower of Babil. From there, he intended fire a beam to release Zodiark from his prison. Despite the Scions' attempts to stop him, Fandaniel had Zodiark destroyed, His death causing the protective shroud of aether to dissipate, resuming the Final Days. The stagnation that followed rotted away the aether of those who succumbed to despair, due to being sundered souls compared to the ancients, transforming them into blasphemies. The Warrior of Light traveled back in time and gained Venat's aid in learning of the Meteion, escaping the memory-alteration spell Hermes inflicted on himself and Emet-Selch.
Persuading the Sharlayan Forum, the Scions were granted access to Aitiascope, so they could talk with Hydaelyn. After passing Hydaelyn's final test, the Scions received a crystal that contained the record of Meteion's location. With the aid of the Loporrits, the Scions were granted the use of the starship Ragnarok to travel to Ultima Thule at the edge of creation where Meteion made her nest. Meteion kept insisting that life was suffering and despair, but the Warrior of Light, holding on to hope and their own reasons for living, kept resisting. When they finally came face to face with Meteion, the Warrior used the crystal of Azem to bring forth Emet-Selch and Hythlodaeus. The pair used creation magicks to summon an Elpis flower field and restore the Scions who had sacrificed themselves earlier to allow the Warrior to progress. The sight of the flower field restored Meteion's individuality, and she begged the Scions to end the song of oblivion. They fought their way to the Meteia as they converged into the Endsinger. The Endsinger's power forced the Warrior of Light to send their friends out of harm's way, and they resolved to fight it alone. With the unexpected arrival of Zenos Galvus, the Warrior defeated the Endsinger, leaving only a single Meteion as a sole member of the Meteia. By sharing their feelings with this Meteion, she understood the error the Meteia had made; there was never a single answer to Hermes' question, because every sentient being has to find their own meaning in life. Meteion found her hope again and sang one last song of hope, ending the Final Days.