Soulsong (Lightning Returns)

Story
The Soulsong, in Lightning Returns, refers to the ceremony proposed by Bhunivelze to be performed on the final day of the world, Nova Chrysallia. The Soulsong can only be performed by the saint who can hear the voices of the dead, Vanille, who obtained the ability strangely after awakening from crystal stasis 13 years prior to the the game's events. Vanille would, however, die from performing this ceremony. She was fully aware of this yet wanted to go through with it to atone for her past.

Thirteen years before Lightning awakens from her crystal sleep, Oerba Yun Fang and Oerba Dia Vanille awoke from their own in the city of Luxerion, under the care of the Order of Salvation. When the Order discovered Vanille's ability to hear the voices of the dead, it became interested in her and came to seek the holy clavis, an ancient relic with the power to summon the souls of the dead. Fang learned the Soulsong will kill Vanille if she carries out the ritual, and ventured off to the Dead Dunes in hopes of finding and destroying the clavis to save Vanille.

The Soulsong is a ceremony that would call all the souls of the dead to the Holy Clavis so that they may be eased of their suffering in the chaos. When in reality, the Order was told by God, Bhunivelze, to cleanse the world of the unclean souls so that when they enter the new world, the worthy souls, those who survived in the chaos for the past 500 years, would be free of grief. However, they lied to Vanille, claiming the Soulsong would only "ease their suffering".

Fang discovered the truth behind the Soulsong 13 years before the game's events and left the Order's protection and Vanille to go in search of the Holy Clavis, which was hidden in the Dead Dunes in hopes of finding it before the Order to save Vanille's life. During the Dead Dunes Main Story, Lightning aids Fang in search of the Holy Clavis in the Dead Dunes ruins. After traversing through the ruins, the two find the Clavis yet find the Order's Secutors surrounding them, led to them by Lumina. The Order then stole the Clavis and fled to Luxerion.

On the Final Day of the world, Lightning rushes to the Cathedral to save Vanille and all the souls of the dead who would be destroyed by the Soulsong. She rejoins Fang in the Cathedral halls and they fight their way to Vanille, who is in the middle of performing the Soulsong. The two fight off the Order and tell Vanille the truth behind the Soulsong and how she can guide the souls of the dead to the new world instead of destroying them. The High Priestess then intervenes and forces the ceremony upon Vanille, Snow then crashes into the room through the ceiling and destroys the Clavis, stopping the Soulsong once and for all. Vanille then, with Fang by her side, guides the souls of the dead to the Ark in the sky to be reborn in the New World. Lightning then saves Fang and Vanille's soul.