The Blackstone Fortresses

The Blackstone Fortresses are relics of a vanished age, six vast star-fortresses of black stone and unfathomable design left drifting in the Gothic Sector by hands no living race remembers. For millennia the Imperium held them as curiosities and mustering-points, never grasping the sleeping terror within their bones. They were not mere fortresses at all, but instruments of a science older and darker than mankind's dreaming.

When Abaddon the Despoiler launched his Twelfth Black Crusade, the warmaster of the Chaos Space Marines seized several of these leviathans and awoke their true purpose. Linked together, the fortresses could unleash a beam of annihilating energy powerful enough to snuff out a star and immolate every world in its light. Whole systems were extinguished as Abaddon wielded the ancient weapons against the servants of the Corpse-Emperor.

Their surfaces crawl with unknowable machineries, and lesser minds that dwell too long within their halls are drawn into madness or corruption. The forces of the Dark Gods flocked to them as to holy sites, sensing the malign power thrumming in their depths. Only at grievous cost did the Imperial Navy wrest a portion of them back.

To this day the surviving Blackstone Fortresses remain among the most dangerous artefacts in the galaxy, coveted by Chaos and Imperium alike, their full potential a secret that could unmake the stars themselves.