Fear will strike at the hearts of its people. They will know that death has come to them.

Hol Beloth's body is a searing furnace. His skin smokes with it and the rotten smell of sulphur fills his nose and mouth. It seems the Dark Apostle is not the only one on the verge of a transformation. Hol Beloth has longed for this moment since first he set foot on Calth, and he can literally taste his reward.

Eriesh Kigal and his Terminators lead the way, climbing higher with every passing moment. The cave is wide and filled with gunfire. A squad of Ultramarines and some uniformed mortals in the colours of the Defence Auxilia are shooting at them. They cower in hastily-erected barricades. He sees that each man has a black X daubed somewhere on his armour. He does not understand the significance of this, and dismisses it as irrelevant.

Hol Beloth feels a stinging sensation at his chest and sees a black burn scar from a las-impact. The skin is curdled and scorched, but he feels no pain. None at all.

The tunnel turns and widens, its ceiling rising up to almost thirty metres. More soldiers are moving to intercept them. Gunfire intensifies. None of it matters. Three Ultramarines attempt to impose order on the few soldiers at their disposal. A pair of armoured vehicles rumble into view, a Rhino and a civilian cargo transporter with a pair of heavy stubbers welded onto a primitive turret.

The Rhino's guns hammer the Terminators, and one of the mighty warriors stumbles as the heavier weight of fire finds a weak spot. Hol Beloth wonders why it is taking so long for the Ultramarines to respond to the terrible threat in their midst. Then he understands the sacrifice of Foedral Fell.

The Ultramarines are not here. Not in any numbers of significance.

The gunner of the Rhino brackets the wounded Terminator and hammers him again and again. It is a successful tactic, as the percussive chain of explosions eventually cracks the armour open. The warrior within is cut apart and his armour sags with his death.

Maloq Kartho leaps into the air, his reverse-jointed legs powering him over the heads of the Ultramarines. He is in amongst them, his clawed arms like threshing blades. He rips them apart, tearing war-plate open with his bare hands and hurling body parts aside like butcher's waste. Bolt rounds flatten upon his iron-hard flesh, blades bounce off him; his laughter is that of a being who has achieved his heart's desire and found it more wondrous than he ever hoped.

The Ultramarines are dead, and Kartho charges the Rhino. Its driver sees the danger and guns the engine. The tracks spin furiously, but not fast enough Kartho smashes into the vehicle like a wrecking ball. The hull of the Rhino buckles inwards explosively. Flames rip from within and the engine gives out with a hard bang of combustion.

Kartho's charge has broken the tank in two. A sweep of his bulging arms hurls the wreckage away.

Eriesh Kigal kills the up-armed civilian transporter. A hail of high-impact rounds blows its engine block apart and the explosion lifts it ten metres into the air.

His Terminators are unstoppable juggernauts; small-arms fire is an irrelevance and they are proof against most blades. Storms of fire batter the curved plates and layered plastrons, but none of it has any effect. An unstoppable line of armour pushes inexorably forward, climbing higher into the arcology with every passing moment. The armed forces that remain here will be mustering above, but they will be too late to prevent the wholesale destruction of Calth.

There are too few defences here to stop the Word Bearers. In their arrogance, the Ultramarines think they are secure, that their way of doing things is the only way. Blind to the virtues of free thinking, the XIII have sealed their fate by clinging to an outmoded way of war. The old ways are gone, and a new order is rising.

The Ultramarines have failed to embrace that. It will be their undoing.

Hol Beloth grunts in sudden pain. The enemy has not wounded him. This is not the already forgotten pain of a gunshot or a sword cut. Things are breaking inside his body. Bones shift, elongate. Organs squirm and reshape themselves. Blood grows sluggish as its composition alters. His vision blurs as nictitating membranes form over his eyes. Old pain diminishes and new pain replaces it.

Hol Beloth throws away his sword. The blade is broken just above the hilt, but he has no memory of it snapping. He has a dagger at his hip, one of the crude, flint-bladed things Erebus presented to the anointed ones. He does not draw it.

He has no need of it now, for his fingers sprout claws like sword blades.

Flames and the cries of the dying are all that they leave in their wake.

More slaughter awaits ahead.

Hol Beloth ascends into the administration level of Arcology X.

He sees thousands of mortals cowering here, clustered around a building of polished white marble. He no longer sees as he once did. His sight is that of a voracious predator.

His world is blood hues, flesh smells and fear-stink.

It is good.

XXXVI.

The Defence Auxilia and Ingenium Support Division are responding with incredible speed. Army units integrated into the chain of command are already in place, but Hamadri fears it is too little, too late. She watches the Word Bearers fight their way into the sprawling administration level from the upper hatch of a Chimera.

'How they can be here?' she asks herself, knowing that the question is meaningless now.

Captain Ullyet is already fighting, his Salamander command vehicle racing back and forth at the entrance to the sub-caves. No sooner had Sergeant Ankrion's warning of the breach in the lower levels gone out over every active vox-network than the tanks of the 77th Support Division roared into action.

His vehicles are cargo carriers, engineering rigs and combat support tanks armed with anti-personnel weapons, they are no match for Space Marine Terminators. The Defence Auxilia moves to assist, Hamadri's orders sending her tanks around the flanks to keep the enemy boxed in.

Her Chimera bounces over the uneven ground and Hamadri sees how few enemy warriors there are: six Terminators and a Dreadnought, and two monstrous things to which she can give no name. One is taller than the Dreadnought, its flesh blackening even as she looks at it, as though it burns in a fire she cannot see. The other is a hunched, swollen thing with scraps of blood-red plate embedded in the mass of its body. Its engorged muscles expand like overfilled fuel bladders and its arms end in flailing bone-swords.

It would, on paper, be a paltry force with which to invade Arcology X.

But it may well be enough.

'Bring us in on the right,' she orders her driver.

The Chimera slews around, its tracks spitting rock fragments. Hamadri brings the rotor cannon around and depresses the firing triggers. Thudding recoil slams back against her palms, but she keeps the weapon on target. A stream of bullets strikes the monster with the bone-swords, and her shots only falter when the thing looks up at her with eyes that are windows into madness.

The beast vaults into the air, an impossible leap. Hamadri cranks the pintle-mounted weapon around and opens fire. The angle is too steep, her shots too low. The creature lands on the Chimera's frontal section with a ringing hammerblow. The impact is colossal, its weight out of all proportion to its size. The Chimera's hull is crushed and the tank turns end over end like a flipped aquila coin.

Hamadri has a fraction of a second's life left.

She wonders if her son in the Numinus 61st is still alive. Better that he is dead than have to fight a war against such monsters.

The Chimera slams down on its topside and Colonel Riuk Hamadri joins the long list of those killed in action.

XXXVII.

The change is upon him.

His flesh is becoming. The rituals have been observed, the sacrifices made.

Maloq Kartho has attracted the eye of the gods and he feels the immense power that awaits him. He awaits the judgement of his worth. The muttering shadows are gone, drawn to the trap in Foedral Fell's stronghold, but he has no need of them now. He will be his own shadow now, shedding his old identity and clearing out what could have been.

The last piece of him awaits his final offering.

He still senses the warp power's unwillingness to give up its hunt. It has its prey practically in its jaws, but his need is the greater. Without that power his frame will explosively mutate. It will be cast down in a wallowing pit of mindless depravity. A worthy fate for some, but not for him.

He watches Hol Beloth kill with ferocious abandon.

The commander's mind has fractured and this last betrayal is the pact with which he seals his bargain with the monarchs of the warp. Eriesh Kigal's Terminators are still in the fight, though another one has been brought down. The enemy is rallying and bringing their heavier guns to bear. They still think the Word Bearers are here to conquer, to capture.

He laughs, and those mortals who hear him fall dead instantly.

Kartho turns to Zu Gunara.

That name is meaningless. Zu Gunara died for the second time weeks ago. The Dreadnought that once housed his flesh still carries the bio-weapon and now it holds it out to him like an offering. He supposes that is exactly what it is.

The life eater virus is a gift from the gods.

The fighting continues behind him, but he no longer cares.

Kartho opens the arming panel and enters the codes he memorised long ago when the scrapcode attack first compromised Calth's defence network. The virus bomb's circuitry comes to life and a green light bathes the interior of its arming mechanics. The cog-skull insignia of the Mechanicum and the Ultima of the XIII Legion flash baleful warnings. No provision exists for instant deployment, only a preset countdown. It will make no difference.

More warnings chime from the interior of the bomb as he unlocks each security protocol. He ignores them and turns the final arming trigger before snapping it off. Numerous failsafes and redundancies exist to reset the countdown. Kartho destroys them all.

The bomb broadcasts a final countdown signal across a multitude of vox-bands and sets off an unmistakable alarum bray. Such warnings are pointless. Anything close enough to register them will be killed by the release of the virus within minutes.

He sees the realisation of what he has done spread through the Imperial soldiers. Those who don't recognise the threat of the virus bomb's shrieking warning learn through the vox what he has brought into their midst. Soldiers turn and flee. Armoured vehicles blow their engines as they throw their tracks into reverse. The panic and terror is almost overwhelming and Kartho roars with laughter as he sees the vaunted Ultramarian discipline collapse in the face of certain death.

A few braver souls run towards the bomb, perhaps thinking they can disarm it. They are deluding themselves.

He feels his bargain with the warp sealed in the depths of his transforming flesh.

His body has been prepared and now the communion of material and spiritual can take place.

Kartho lifts his hand and sees a glimmer of silver wreathe the tips of his claws.

His very flesh is a knife with which he can cut through the dimensional walls. He senses this is borrowed power, a fleeting gift to enable his union with the warp.

Kartho slashes his hand down through the air and the material wall of the universe parts before him. A poisoned wind gusts from the deep wound, a gateway to the domain of gods and monsters. Soon he will be both.

He feels another of Kigal's Terminators die.

His senses are beyond anything he has known before, and this is just the beginning of his ascension. He pulls the wavering tear in the universe wider, tasting the dark promise of the miasmic void beyond. This will be his realm now, not the tasteless material plane of mortals.

But just before he steps through, Maloq Kartho experiences something he thought long since bled out onto the sands of Colchis.

He knows doubt.

He turns from the howling gate in time to see a pair of rad-scarred Land Speeders streak into the cavern. Their engines are overheating and flying on fumes. They have been pushed far beyond their limits to get here.

A pointless gesture.

This bomb will detonate. Nothing now can prevent that.

Riding tall in the lead skimmer is an unhelmed warrior in blue and gold. Maloq Kartho has never seen him before, but his transformed senses recognise him immediately.

Remus Ventanus.

XXXVIII.

The administrative level is in chaos. Civilians and soldiers alike flee in terror from the figures standing at the heart of the cave a Dreadnought, and a thick-limbed figure of black scales whose body seems to flicker with dark flame. This is the leader of this dark host.

Ventanus knows it in his bones.

The Dreadnought carries the screaming bomb in its hands, and every frequency is telling him that the life eater warhead is on the verge of detonation. A Word Bearers Terminator is still fighting, but Sydance's speeder is diving towards him. The Terminator has armour that can survive impact with a super-heavy.

Sydance has a multi-melta.

He sees a flash and hears the roar of superheated air, but he doesn't see what happens to the Terminator. The speeder lurches, its engine spluttering its death rattle. That it has brought him this far is nothing short of a miracle.

Selaton has pushed the engine as hard as he can and now it is done.

'Take us down,' Ventanus yells over the screams and chatter of gunfire.

Selaton nods. 'Don't think we've much choice, captain.'

Before the speeder can descend, Ventanus hears a bestial roar. An abominable creature with sword blade arms vaults from the back of a crushed Rhino. It is coming straight at them.

'Incoming!' he yells.

The speeder heels over as Selaton wrenches it around, but even legionary reflexes aren't quite fast enough. The creature's bladed arms slice the vehicle in half, taking Selaton's legs at mid-thigh. Ventanus leaps clear as the speeder ploughs rock and wrecks itself in an explosion of flying steel.

He lands at the run and has his bolter out a second later.

He does not know if Selaton has survived the crash, and has no time to check.

Ventanus confronts the beast that was once Hol Beloth The beast that brought them down rears up, a wall of expanding tissue and claws. He sees it was once a man, a legionary like him, but whatever hypermutations are wracking its frame are completely out of control. Limbs burst from gristly tumours and fanged mouths erupt across its malleable flesh.

Ventanus empties a magazine into the creature. His shells punch through its metamorphosing body. He hears the detonations, but the creature does not even appear to feel them. He reaches for another magazine, but a heavy paw the size of his chest slams him to the ground. Its bulk is enormous, swelling and evolving in an uncontrolled frenzy.

He reaches for his sword, a chain-weapon taken to replace his lost powerblade.

The creature is screaming. He cannot tell if it is in anger or pain.

Ventanus thrusts the sword into the rippling folds of new flesh and the suction is so great that it tears the blade from his grip. The monster's body swallows the chainsword whole and Ventanus reaches for his next weapon he unclips a pair of frag grenades from his belt, one in each hand.

Part of him knows that this is folly.

The life eater virus will destroy the monster, regardless of this fight's outcome, but it matters to Ventanus that it dies by his hand.

He punches the grenades into the thing's body, releasing them before his arms suffer the same fate as his sword. Both grenades detonate with a wet thump, showering him with rancid flesh as raw as protoplasm. Open wounds gape, bloody and stringy with unformed matter.

The creature doesn't die. It is too large now, but he has hurt it.

It shrieks from its hundreds of mouths. He has a moment at best to capitalise on its pain.

Then he sees it.

In one gaping wound is a grey-bladed dagger, a weapon clinging to a leather belt that has been subsumed by the expanding flesh of the monster.

He knows what it is. He has used such a weapon before.

Hating that he has no choice, Ventanus reaches in and drags the dagger from the sopping, fleshy wound. He feels the legacy of murder imbued in the glitter-sheened blade. This weapon has a bloody history, but it also has power and he needs that now.

It is a pitifully small thing to wield against so bloated a foe, but Ventanus has first-hand experience of what harm such weapons are capable of wreaking.

The monster's face looms over him, a bloated mass of gibbering mouths, lunatic eyes and lashing tongues. Whoever this once was, he is long gone. Ventanus wonders if he understands what he has become.