The Aggressors broke into a jog that shook the bridge. The Intercessor squads lowered their bolt rifles from fully-aimed positions and cradled them at their hips, switching from single shot to short-burst mode. The greater ammunition expenditure was worthwhile, for it maintained fire efficiency when moving at speed when shots could not be perfectly aimed.

As precise as any Mechanicus machine, the forward party made the other side, turned, and took up position around the guard walls of the spire ramps.

Engines screeched in the spire shaft, jarring with the hideous wind music – jet turbines, grinding hard for want of lubricant. Felix risked a look below. Seven heavy three-engined drones were rising rapidly up the shaft.

‘Ware!’ called out Codicier Maxim. ‘These are daemon engines! I can taste their souls.’

‘Destroy them,’ said Felix.

Bolts and plasma crossed the shaft, skewering the lead drone from multiple directions. Its armour cracked moistly, like chitin rather than plasteel. An engine blew out, and it whirled down to destruction.

‘More coming in from above!’ voxed Sergeant Brutian of the second Hellblaster squad.

The dead spire’s acoustic design made it a sounding chamber where every noise was amplified massively. Bolts exploded like heavy mortar rounds. Air superheated by plasma streams exploded with the force of tropical storms.

The lower drones were in a poor firing position. At their angle of attack, the Primaris Space Marines were well sheltered by the ramp and walkway walls. Gouts of sticky, yellow plague liquids splashed against the building’s fabric, eating into the metal and causing fleshy boils to sprout and blood to flow around the impact sites in violation of all natural law.

For the descending daemon engines, however, the converse was true. The sprays of infected matter they pumped from their cannons came over the top of the walls, washing over the Space Marines. The paint bubbled on their armour, and warriors fell with pained cries as the vile material ate through their softseals and into the flesh beneath.

The two Librarians worked together, nullifying hexes and banishing the trapped daemons back into the warp. Three of the drones fell this way, and another two to the concentrated fire of the Primaris Space Marines, before the strike force’s attention was diverted elsewhere.

‘Captain, I have multiple contacts coming from below on the ramps,’ shouted Hellicus against the crack and boom of battle. ‘Some kind of infantry. There are thousands of them.’

Felix retasked his suit’s auto-senses to take a sounding even as he fired his gauntlet bolter, riddling a bloat-drone hovering up before him with explosive rounds. His attack knocked it back through the air. Cratered metal-flesh weeping thin liquids, it dropped out of sight.

Felix’s auto-senses indicated his scan was done. He rotated his cartograph. The walkways were so crowded with enemy contacts that they were a solid red.

‘More coming from behind,’ voxed Flavian.