Blue-white serpents of electricity burst from Librarian Best's palm again, their air-rending shrieks briefly drowning out the roar of machinery.
The psychic lightning did not scatter at random. Like a swarm of unerringly precise snakes, it slipped into every gap in the congested passage ahead.
Every Construct it touched erupted in blinding electrical sparks. Metal shells buckled under the overload, and the blasphemous flesh embedded within them carbonized instantly.
More than a dozen humanoid iron carcasses stiffened mid-spasm and fell, becoming smoking obstacles that the next wave of their kind trampled to pieces. The passage cleared briefly.
"Passage clear! Everyone, follow me!"
Dexter's voice cut through the howling Bolters and the screech of snapping metal.
The Power Sword in his hand traced a cold, gray-blue arc, piercing a Construct shaped like a flayed hound from jaw to tailbone as it lunged from the shadows at his flank. Filthy coolant splashed across the wall.
A flick of the blade sent the wreckage flying. His stride never faltered, and his Power Armour boots crushed scattered components beneath them with a teeth-grating crunch.
"Hold formation! Watch the pipes on the right!"
The squad pushed deeper.
The space gradually widened as they advanced, expanding from a low tunnel barely broad enough for a few people into a vaulted corridor wide enough for two Rhinos abreast.
Sparse emergency lights cast wavering patches of dim yellow over rusted pipes and structures dripping with condensation.
Yet the open space brought no respite. It merely offered more angles of attack and stranger enemy silhouettes.
Beyond the endless waves of standard Constructs, stitched together from crude metal and pale flesh and charging at them with shrieks, more blasphemous creations began to appear that defied classification.
There were many-legged mechanical spiders that ambushed them from ventilation ducts overhead, spitting corrosive