The war machine rose like a plasteel and ceramite mountain over the Astartes, its Hydra flak batteries and mega-bolter turrets along its flanks traversing to bear on the enemy ranks. The multi-barrelled laser batteries opened fire, unleashing a torrent of bolts at the stationary battle tank. The tank all but vanished in the glare of hundreds of detonations as the laser bolts pounded the armoured hull. Individually, each shot lacked the power to penetrate the mighty tank's reinforced ceramite plates, but one among the hundreds of impacts landed a direct hit on the plate steel bolted hastily over its former wound and burned straight through. Smoke billowed from the tank's open ports as the thermal effects of the bolt incinerated the crew in a split second.

A pair of mega-bolters roared to life next, sending a stream of heavy calibre shells over the heads of the Dark Angels and into the enemy's ranks. Rhinos shuddered beneath dozens of hits and were torn apart in seconds; the Astartes standing alongside them fared little better. The Sons of Horus recoiled under the storm of shells; dozens of the warriors fell, their armour riddled with holes. The rest wavered for a moment more and then broke, retreating swiftly back into cover among the surrounding buildings. Mega-bolter shells pursued them the entire way, slaying a dozen more before the rest could escape.

The Dark Angels stood in the shadow of the immense war machine, wreathed by wisps of fyceline propellant from the barrels of the mega-bolters and numbed by the awesome roar of the guns. Alone among them, Lion El'Jonson turned to the enormous engine and raised his sword in salute.

'Well done, Brother Titus!' he called over the vox. 'You could not have arrived at a more opportune time.'

'Techmarine Askelon deserves your accolades, my lord, not I,' replied Titus's synthetic voice. 'It was no small feat merging my MIU with the war engine's interface without access to the original STC blueprints; only the specialised tools and equipment in the assembly building allowed him to modify the vehicle's interface with my neural connectors. I regret that I am still unable to access the vehicle's shield array, and my locomotion is still very slow and clumsy, but all weapons systems are fully functional.'

Jonson stared up at the mountain of metal. 'Brother Titus, can your surveyors detect the star port to the south?'

'The unit is in need of calibration, but yes, I am registering it on my array,' Titus replied. 'I am detecting twelve heavy transports and numerous small vehicles.'

The primarch nodded. 'Load a shell into your siege gun and destroy the site.'

Titus hesitated for only an instant. 'At once, my lord,' he replied. With a ponderous moan of heavy-duty motors, the giant cannon barrel began to elevate. 'Loading will complete in five seconds,' Titus said. 'I advise that you take cover behind me. I cannot adequately gauge the effect the gun's concussion will have when it is fired.'

As primarch and war machine spoke, Nemiel cast his gaze upon the devastation that Titus had wrought. Scores of Astartes lay dead, surrounding misshapen metal hulks that were functioning APCs just a few minutes before. Behind him, heavy plasteel machinery rattled and groaned as the siege gun's auto-loading mechanism fed a magma shell into the cannon's breech. Recalling what such shells had done to the forge, he felt a deep sense of dread. What horrors could a warlord wreak with such weapons at his command?

The Astartes withdrew a hundred metres behind the huge machine, nearly to the entrance of the assembly building itself. Nemiel glanced over at Jonson, and saw the primarch staring off to the southwest, towards the unsuspecting star port.

The air blazed with a flare of orange and yellow light as the cannon fired, rocking the massive war machine back against its drive units. Nemiel felt the concussion of the blast like the fist of a god striking his chest; several of the Astartes staggered beneath the blow, while downrange the pressure wave hurled the wrecked Rhinos about like broken toys. The magma shell roared skyward, flaring like a snooting star until it was lost from sight behind the planet's thick overcast.

They waited in silence, counting the seconds as the shell reached its apogee and began to fall to earth once more. Two minutes after the shot there was a flash of searing white light on the southern horizon, followed by a furious rumble that shook the earth where the Astartes stood, more than thirty kilometres away. A hot breeze wafted against their faces, smelling of molten steel and ash, and a slowly-rising pillar of dirt and debris climbed portentously into the sky. With a single stroke, the enemy ground force had been utterly destroyed.

'Such is the fate of all traitors,' Lion El'Jonson said. The implacable look in the primarch's eye made Nemiel's blood run cold.

TWENTY

The Conqueror Worm

For the third time in twenty-four hours, Zahariel found himself locked into the jump seat of a Stormbird, his ears full of thunder and his eyes brimming with dark thoughts.

The angels of Caliban's deliverance descended on the Northwilds arcology clad in fire, smoke and burnished iron. Luther had ordered a ballistic approach for the assault forces, so the drop ships literally fell from the sky upon the beleaguered city. To the panicked Jaegers securing the landing platforms on the arcology's upper levels it was like a scene from a mythical Armageddon.

The command squad went in with the first wave. Zahariel's stomach leapt as the transport pulled out of its dive less than a thousand metres over the arcology and the Stormbird's pilot gave full power to the thrusters scant seconds before touchdown. His gauntleted hands tightened on the haft of the force staff resting between his knees as he counted down the seconds until landing. Around him, the other members of the squad made final checks to their wargear with swift, practised movements. The atmosphere in the troop compartment was electric. Even Brother Attias seemed unusually animated, his steel-plated head turning left and right as he spoke words of encouragement to the Astartes at his side. The words of Luther's speech on the embarkation field still rang in their ears, calling them all to glory.

The moment has come, brothers. Jonson has cast us aside; the Emperor, who once demanded our fealty, has forgotten us. Now we must decide whether to accept their judgment and give in to the darkness, or to defy them for the sake of our home and our people.

He glanced across the compartment to the jump seats nearest the ramp. There, the Saviour of Caliban sat, clad in his gleaming armour like a hero of old. Luther's gaunt features were composed as he studied page after page of arcane text from the ancient grimoire propped across his knees. Lord Cypher sat closest to him, arms folded across his chest. He stared back at Zahariel from the depths of his hood, his expression unreadable.

Zahariel focused on his breathing. Images came and went in his mind: Sar Daviel, wreathed in tongues of blue fire; Luther, marked with glowing runes and haloed by the same terrible flame; Brother-Librarian Israfael, smoke rising from the wound in his chest, his features distorted with anguish as he sank slowly to his knees.

Shall we side with those who scorn us, or choose our own path, to protect the innocent from those who would exploit and corrupt them?

The noise of the thrusters rose to a screaming crescendo, and then the Stormbird touched down with a tremendous, spine-rattling jolt. Jump restraints released with a metallic clatter and servomotors whined as the assault ramp deployed, letting in the cold, smoke-tinged air of the Northwilds. Boots thundered as the Astartes leapt to their feet; bolt pistols cleared their holsters and chainswords roared to angry life. Zahariel felt his body respond without conscious thought, caught up with all the rest in the intricate dance of death.