Fall of Costov

The Fall of Costov was a lamentable event in the history of the formerly loyalist Astral Consuls Space Marine Chapter. When they were wrongly accused by the Inquisition for crime they didn't commit, without provocation, the overzealous Inquisition decreed the fate of their Chapter homeworld of Costov and subjected it to Exterminatus. Forced to fight their way through the Imperial blockade, the remaining battle-brothers of the Chapter fled and made for the Immaterium. During their long sojourn, their morose Chapter Master received an unexpected and mysterious visitor, in the form of a Word Bearer Heretic Astartes, who whispered promises of power and vengeance against those who would dare cast aside such a noble and honourable Chapter. Filled with dark visions of power and prestige, the corrupted Chapter Master began to preach a much darker creed, prostolising their newfound faith in the Dark Gods, and so, the formerly Loyalist Astral Consuls gave themselves over, body and soul, to the Ruinous Powers and became the notorious Chaos Warband, the Forsworn.

History
Created during the 20th Founding in late M35 to reinforce the regions of space in the Chiros Sector of Segmentum Tempestus, many details of the Astral Consuls' gene-seed and campaigns have been classified by order of the Inquisition. However, during their time, the Consuls were meticulous with individual fighting skill and fierce on the battlefield, performing their duties with admirable efficiency, including the destruction of an alien planetary civilization known as the Aeur. But as the Aeur were noticeably utilizing the powers of Chaos, the Ordo Xenos had accompanied the Astral Consuls into the battle to destroy the Auer.

During the war against the Auer, it was noted by both the Consuls and the Ordo Xenos that the xenos warriors seemed to shimmer strangely and even teleport seemingly at will. And due to the reliability of the usage of this, it was surmised that the Auer had somehow created stable teleportation technology. And after the alarmingly bloody campaign for a single planet, the Inquisition took many corpses and bits of the Auer's creations with them to be studied, or destroyed.

It would not be very long, however, that the Auer artifacts would remain in the hands of the Inquisition. Shortly after being transported to the nearest Inquisitorial Vault, the entire complex was suddenly attacked by a force so mighty that all inside the Vault were dead in minutes, and the Auer items taken. After it was discovered the raid had occurred, recovered pict-feeds showed what looked to be Space Marines with a color scheme matching that of the Astral Consuls. With this news, a fleet of the Ordo Malleus was called to the Astral Consuls' homeworld of Costov to confront the Astartes.

Confused and outraged at the accusation of breaking their honor and stealing from the Inquisition, most of the Chapter vehemently denied the crime of raiding the Inquisitorial Vault, but their firm resistance had only sealed the fate of Costov. Failing to submit to the Ordo Malleus' demands, the Inquisitorial fleet's guns were fired upon the planet - beginning an Exterminatus of the doomed world. Attempting and failing to fight back, the Astral Consuls were forced to flee into the Warp to escape the guns of the Inquisition.

In grief and rage, the remaining of the Astral Consuls Chapter drifted in the Warp for years, realizing that the very Imperium that they were created for and pledged to serve, had now cast them out. For those many long years travelling in the Warp, Chapter Master Arkann Dionus sat silent on his throne on the Chapter's Battle Barge, Angel of Storm, until suddenly another Astartes suddenly appeared before him, as if from thin air. The strange Space Marine identified himself as Kazrand, and as a friend. Kazrand, the Word Bearer, comforted the crestfallen Arkann with confident assurances and honey lies, "We are all too similar, my child. I too, have felt the burning wound that is betrayal by one's supposed superiors. But... there is always a choice- always a decision to avenge the wrong done to you and your brothers..your WORLD."

And so, Kazrand began the work of reunifying the Astral Consuls into great sermons to the Chaos Gods, and demonstrated that if they would be abandoned by the Imperium, then they would abandon it and be granted far greater powers, and avenge Costov. It was said that after this Dark Sermon, the members of the Consuls experienced a sharp pain in their eyes, followed a disorienting new sense that seemed to connect them to their brothers. Praising this as an early gift of the Gods, Kazrand had won over the disenchanted Chapter, who were now eager to enact their revenge. The Chapter fell wholly, body and soul, to the worship of the Dark Gods and were transformed, becoming the infamous Chaos Warband known as the Forsworn.