Trygon

The Trygon, known to Imperial savants as Tyranicus subterra-extremis, is a titanic serpent of chitin and muscle so vast that it dwarfs even a Carnifex. Its entire body is engineered for one astonishing feat: to swim through solid rock. Powerful digging limbs, acid-secreting glands and sheer brute strength let it bore through a planet's crust at frightening speed, driving tunnels wide enough for whole broods to follow in its wake.

As it burrows, an ever-shifting carapace of armoured plates generates a fierce bio-static charge that crackles the length of its frame. This energy fuses the walls of its tunnels into a smooth, glass-like silicate that keeps them from collapsing, so that behind every Trygon lies a ready-made highway into the heart of an enemy position. Its emergence is therefore rarely a solitary event; it is the opening of a door through which the swarm floods.

When at last it rears up from the earth amid its foes, the Trygon is a devastating close-quarters killer, lashing out with six taloned limbs and rows of dagger teeth while discharging its stored bio-electricity in a searing, ionised spray. To defenders it is the worst kind of ambush made flesh, an enemy that appears without warning from directly beneath their feet and drags an entire army up behind it.