Overview
BR-004 is a Black Ring that descended in Keylan Square on 112.8.20. The Ring lasted only 7 days before it was eliminated, becoming the first known Black Ring ever to be stopped after its descent. Its Corpus called down the Ring by devouring Zoya, with an additional contribution of energy from Earl. Zoya's wish was for destruction, and so the Ring manifested her spiritual realm as a desolate wasteland where the ground is dotted with weapons jutting up out of the earth, and the skyline is dominated by rows and rows of rusty iron towers that collapse upon each other at any second. The air is constantly filled with the sharp sound of breaking metal. The Ring distorted space such that moving towards the Statue of Keylan was a shorter distance than moving away from it, and the interior space of the statue was greatly enlarged.
BR-004 was the culmination of a decades-long conspiracy by Parma to corrupt DisCity authorities, especially the Public Security Bureau, and reduce Syndicate to a lawless hellscape. In the violent and chaotic environment of Syndicate, powerful individuals were combined with intense physical and emotional suffering to produce what he considered to be magnificent Black Ring.
Descent
At the sham negotiation between Zoya and the Public Security Bureau in Keylan Square, Zoya was baited by Parma and attacked, then overwhelmed by multiple Inheritances, which Parma produced from within a mysterious black cube. Zoya fought against the Inheritances' contamination long enough for the Chief and 036 to reach her and attempt to stop the descent of the Black Ring, but Earl intervened at the last moment. Bitter at the final betrayal by the authorities and the destruction of The Legion in the ensuing Mania crisis, Earl refused to allow them to kill Zoya, saying that saving the rotten city was not worth her life. He willingly offered Zoya the Inheritance that had been sealed by the Legion in the unclaimed crypt, giving it enough power to evolve into a Black Ring. Zoya and Earl's bodies were then both incorporated into the Ring's Corpseborne.
Elimination and Aftermath
BR-004 was eliminated only a short time after its appearance, when the Chief was able to awaken Zoya's consciousness with the Shackles, weakening the Corpseborne so that it could be defeated by their Sinners. The Chief then consumed the Inheritances inside it, and Bai Yi stole Zoya's unconscious body.
Following the disappearance of BR-004, the city entered a two-week Blue Rain purification period. The Legion, having suffered heavy losses, was disbanded, and many of its survivors were taken into custody for questioning. Large scale protests broke out in Syndicate, and the West District Order Management Regulations were suspended, with DisCity reclaiming the right to govern the West District. Paradeisos launched an accountability inquiry to root out corruption in the City Council, Public Security Bureau, and Framework Against Catastrophe, and the Chief of the Minos Bureau of Crisis Control was arrested on suspicion of their involvement with Zoya and The Legion before the appearance of the Black Ring. In the eyes of the Syndicans who had believed in Zoya and the Legion as their leaders for a better future, the events at Keylan Square were seen as a betrayal of Zoya not just by the Public Safety Bureau, but also by the Chief of the MBCC, whom she had trusted.
Enfer awakened as a Sinner when she saw BR-004 appear through her studio window. In faraway Eastia, the descent of BR-004 caused sustained disasters with devastation so severe that it became widely believed in DisCity that the entire continent had sunk into the sea.
Six months after its defeat, BR-004 was partially reawakened by the Corpseborne of BR-002. A resulting increase in residual contamination was detected by the FAC, and investigation of this spike instigated the events that led to the Ten Days of Rustfire and the resurgence of BR-002.