The plan required Ouroboros's efforts in Crossbell and Erebonia simulatenously. In Crossbell they collaborated with the Crois Family of alchemists. In Erebonia they staged a battle between two Divine Knights, with the plan reaching an impasse with Giliath Osborne's involvement. In the end, Ouroboros worked with Osborne to spur on the Great Twilight.
Upon Campanella's return from the Liber Ark with Georg Weissmann's staff containing the Aureole, he enters the Celestial Globe where the six remaining Anguis await. Upon the Grandmaster's advent and reception of the Aureole, she declares the end of the Gospel Plan and the start of the Phantasmal Blaze Plan.
Step 1: Crossbell
- Main article: Azure-Zero Project
The Crossbell portion of the Phantasmal Blaze Plan was executed by F. Novartis and Arianrhod, the sixth and seventh Anguis respectively. Ouroboros assisted the architects of the Azure-Zero Project in carrying out their plan, as it would result in the re-creation of the Sept-Terrion of Mirage, the Demiourgos. To this end, Dieter Crois was provided with the three Gordias-class robots, the Aions.
On the 26th of December, S.1204, after the defeat of Dieter Crois by the SSS, the Azure Tree manifests in the Marshland of Blue, located in the southeast of Crossbell State. Upon reaching the apex of the tree, the SSS finds that KeA has become the core of the Azure Demiourgos, a being who, in addition to mirage, has also gained power over time and space, surpassing the original Demiourgos. Upon defeating the Azure Demiourgos, KeA wishes her power away, turning her into a normal girl, and Mariabell Crois escapes to further pursue Ars Magna.
Step 2: Erebonia
- Main article: Erebonian Civil War
Following the liberation of Karel Imperial Villa, Vita Clotilde recites the Hexen Clan's most forbidden incantation, Lucifen Lied. As a result of this, the Vermillion Knight, Testa-Rossa awakens, summoning the Infernal Castle from below Valflame Palace in Heimdallr. Shortly after reaching the apex of the castle, Rean Schwarzer and Crow Armbrust pilot their Divine Knights and engage in battle. Following Crow's loss, Duke Cayenne asks Vita if that was all she intended to do, and she responds by saying she was "only interested in the battle between Azure and Ashen." Outraged by this, Duke Cayenne pushes Cedric Reise Arnor into Testa-Rossa, awakening the Vermillion Apocalypse. The Vermillion Apocalypse is defeated and Cedric saved, at the cost of Crow's life. After Crow's death and the reveal of Rufus Albarea as an Ironblood, Giliath Osborne reveals that he is still alive, declaring that he is "taking over the Phantasmal Blaze Plan." As a result of this unexpected event, Vita and the rest of the Ouroboros members retreat from the Infernal Castle.
Step 3: Erebonia
- Main article: Great Twilight
As they try to retrieve the Phantasmal Blaze Plan from Osborne, Ouroboros ascertains his actions actually funnel the Phantasmal Blaze Plan and decide to work with him instead. Together they spur on the Great Twilight, bringing the Phantasmal Blaze Plan to completion as they witness the Sept-Terrion of Fire and Earth, the Great One in conjunction, vanish.