They joined the Sisters at the foot of the steps leading up to the altar. They were metres away, but they could not see it.

‘It is here!’ gasped a Librarian. The hard emotional pressure of psychic power gathering strength pushed at the hind parts of the primarch’s brain as the Librarians of the Adeptus Astartes prepared their gifts in response to the hate they felt lurking in the cathedral.

Behold, signed Sister-Commander Bellas. The weapon of the enemy.

She went up a single marble step away from Guilliman, closer to the altar. With a sound like the collective death sighs of a dozen old women, the cloak of darkness blurred and fell aside.

Atop the steps, before the grand altar, was a monstrous device, almost as tall as the cathedral ceiling. A three-legged timepiece of brass and glass and fiendish intention. Throughout its elongated frame, hollow globes held bubbling liquids of no understandable purpose. Three columns of madly spinning clockwork rotated about an axis that, if carefully observed, was not rooted in the material realm. At the top, three clock faces ran backwards. Each one had its own pendulum, and they swung back and forth in a complicated dance outside of the turning columns, barely missing their neighbours at the apex of their travel. Their weights were crescent axe heads made of steel sharp as convent whispers. The air screamed faintly as they swung.

Within the open framework of the clock, dark energies moved sinuously, wrapping themselves around crackling cylinders and clockwork that would have seemed commonplace in any other setting. At the very centre, enmeshed in moving gears and impure psychic power, was a triangular menhir, roughly twelve metres high, composed of a greenish mineral similar to olivine. It stood impossibly inverted, balanced on its point, the mass of it held up by no more than a centimetre’s thickness of stone. It throbbed with the intensity of a migraine, a sluggish heartbeat of despair that sank into the soul. Set on red-rusted iron poles around the clock were three cast-bronze representations of Nurgle’s tri-lobed sigil. They vibrated with inner power, a shimmering heat haze coming off them.

Where the cathedral had seemed silent, now it resounded to a rapid triple ticking and the groaning of gears, as if the clock, once noticed, could not hide its corrupting voice and was revealed in totality.

This is an abomination, signed Sister-Commander Bellas. The servants of Chaos always choose to insult our holy lord where they can.