The Luxerion Cathedral (in Japanese: ルクスエリオン キャセドラル, Rukusuerion Kyasedoraru) is the Order of Salvation's main church within the divine city of Luxerion as well as their seat of power that dominates the city's skyline. A cathedral-like temple built to honor the god Bhunivelze, where the faithful go to pray on a regular basis, and where Vanille lives under the Order's protection.
Vanille resides in the cathedral, where she has remained for the last 13 years being closely watched over by the Order of Salvation, not allowed to leave. After she awoke from crystal stasis, Vanille had gained the power to hear the voices of the deceased and was thus dubbed a saint whose task would be to perform the Soulsong on the eve of the Apocalypse and obliterate the dead and all memory of them from the living's memories. Vanille is unaware of this, however, manipulated by the Order into thinking the Soulsong will grant the suffering souls respite in allowing them to fade.
When the end of the world looms near, Lightning awakes from crystal stasis and is made Bhunivelze's savior tasked with saving the souls of humanity. After hearing of her exploits in the city, Vanille requests to see Lightning who speaks with Vanille's servant, Aremiah, who tells her a precious crystal shard has been lost. When Vanille awoke from crystal stasis, she was grasping a piece of crystal and it has been her precious possession ever since as it lets her glimpse the estranged Fang. Lightning finds the crystal from a delivery company employee who claims someone high up in the Order gave it to them with no receiver's address, and Lightning thinks someone from the Order wanted to steal it from Vanille. Lightning returns the crystal to Aremiah and is granted passage into the cathedral at night time.
Lightning finds Vanille with Lumina, a mysterious girl who resembles a young Serah Farron, Lightning's late sister. Vanille leads Lightning underground to God's Sanctum and shows her a concentration of Chaos around the altar, which Lumina refers to as the "wind of sorrow", lost souls in suffering. Vanille explains the souls of those who died after Valhalla's Chaos burst through Etro's Gate were drawn to the cathedral and that she can hear every cry of their pain. The Order seeks the save the dead from their anguish and needs Vanille to call them to her. Lightning asks if she will be able to handle millions of souls at once, but Vanille answers she doesn't have a choice. Lumina says the souls have been building up for years, and if Vanille does not call them to her and they ever escaped, it would destroy the world as well as the future.
On the world's final day, the dark energy Chaos advances into Luxerion, engulfing the city with Anubyses emerging from its depths, the cathedral remaining as the last safe haven as Vanille prepares to sacrifice herself in the Soulsong. Lightning has learned the Order seeks to use Vanille to destroy the dead and ensure their own salvation in Bhunivelze's new world. With help from Noel, Lightning infiltrates the cathedral and enters the Temple of Light beneath it.
Lightning is joined by Fang as they reach God's Sanctum where the ritual is being performed, and convince Vanille to stop and instead guide the dead to the Ark where they can be reborn. When the final bell tolls, Bhunivelze appears, using Hope as a medium, and captures the souls of Lightning's friends and invites her to witness the birth of his new world. After Mog arrives to help, Lightning goes through the Savior's Trials and forges the Ultima Weapon, and enters the last trial to confront Bhunivelze in the realm of Cosmogenesis.