The gunfire ripped through the servitor. Abaddon rammed through the wreckage of its torso. Pieces of armour and flesh splattered across the ground. Another half-machine clanked forwards on tracks. It fired. A stream of rounds struck Abaddon. His helm lit with damage. Chunks of armour tore from his chest. He ran into the gunfire. Behind him, his Justaerin were firing down into the side corridors.

They were deep under the surface of Luna, in the warren of smooth black stone divided by circular doors and twisted into spirals like the inside of a seashell. The air was still and cold. Mica and crystal flecks gleamed in the walls as gunfire shattered the dark. Even echoing with the sounds of battle the warren seemed quiet, as if the weight of its silence dragged the sound from the air. Abaddon felt it pull memories into the moments between the muzzle flashes, old memories held deep but not forgotten: sharp silver and flesh, water and blood, darkness and blinding pain. This was the domain of the Selenar, the seat of the Luna gene-cults, the place of his rebirth.

Before him lay a circular door set in the curve of the passage wall. Low relief images moved across its surface in silver, figures with crescent headdresses and burning torches. Spiralling haloes of symbols wreathed them: tau-aleph, gamma-kaf. Beyond lay one of the last fanes of the gene-cult, a sanctuary against time and decline. They had come this far, hacking and killing without pause. Most of the resistance came from servitors following blunt battle programs. But those half-machines still had weapons that could kill a legionary.

A figure of piston limbs and armour plates unfolded from a niche in the wall and launched itself at Abaddon. The human flesh that guided it was lost beneath a frame of tarnished silver and black carbon. Stretched out it would have stood taller than Abaddon, but its power had been bunched and folded into the shape of a monstrous feline, six-limbed and blade-clawed. Its head was a fanged mask, with a mane of chromed hair. It was a sacred sentinel, one of the guardian beasts of the Selenar’s inner sanctums. Lightning wreathed its jaws as it leapt.