After Elain’s attack leaves the King of Hybern collapsing, Nesta rises and goes to him instead of to her sister. Nesta takes Truth-Teller, slowly twists the blade through his neck, and completes the death-promise she made in Hybern by severing his head. The violence leaves Nesta momentarily transfixed, and Elain’s horrified cry over their dead father draws the Cauldron’s attention; because it will not harm Elain, it recoils and hurls Feyre away across the battlefield.

As the Cauldron drags Feyre back, Feyre sees that Hybern’s army is still winning even without its king. Rhysand and the other High Lords are fighting in monstrous forms, Helion is close to being killed by Hybern’s commander, Bryaxis is shielding the human forces, and Drakon and Miryam have turned on Jurian while Mor tries to intervene. Feyre also senses Rhysand faltering, which makes the need to end the battle immediate.

Back at the rock, Amren forces Feyre to focus and then reveals the truth she had hidden: the answer in the Book was never a spell to control the Cauldron, but a spell to unbind Amren herself. Amren explains that Feyre, strengthened by facing the Ouroboros, can serve as the conduit for the Cauldron’s power, and that Amren’s released true form can wipe out Hybern’s forces. Varian arrives and begs Amren not to do it because freedom will mean losing the self they know, but Amren accepts the cost, calls her time with them a gift, and admits that loving Varian may have been another gift.

Amren gives Feyre the spell mentally, then takes Feyre’s wrist and throws herself into the Cauldron. Feyre forces the spell through her body and magic until Amren vanishes beneath the dark water and the binding breaks. Varian pulls Feyre back just before a shockwave erupts; the Cauldron splits into three pieces, and Amren rises from it as a blazing being of light and fire, winged and crowned with incandescent power.

In her unleashed form, Amren descends on Hybern’s army and destroys it piece by piece. Soldiers die in fire or at the mere passing of her power, Hybern’s commander is obliterated before he can kill Helion, and Rhysand shouts a warning for their allies not to flee from her. Even as her own strength burns away, Amren continues to the sea and empties Hybern’s ships of life until the last enemy vessel falls silent; when the destruction ends, only bright, clean light remains on the water, suggesting Amren has spent herself to save them all.