The loyalist attack was bending the line of the traitors back, a curving arc of battle with Ferrus Manus at its centre. The screaming raptors of Corax's Raven Guard cut a swathe through the enemy's right flank, his fearsome assault wings dropping from above on the fire of jump packs, and slaughtering their foes with shrieking sweeps of curved blades. Corax darted like a dark bird of prey, leaping through the air with his winged jump pack and killing with every stroke of his mighty talons. Vulkan's Salamanders burned the traitors' left flank, plumes of fire marking the extent of their advance.

But for every success, the traitors thus far had an answer. The terrifying form of the World Eaters primarch cut through hundreds of loyal Astartes as they tried to force a crossing through a killing zone of World Eater support squads. Angron bellowed like a primordial god of battle, his twin swords carving bloody rain through any who dared stand before them. As easily as the traitors died at the blades of Corax, Ferrus Manus and Vulkan, so too did the loyalists die at those of the Red Angel.

In contrast to the brute savagery of Angron, Mortarion, the Death Lord, killed with a grim efficiency, harvesting scores of loyalist lives with every sweep of his terrifying war-scythe. This Death Guard fought with grim tenacity. Where the traitor primarchs stood, none could live, the loyalist assault breaking against them like the tide on immovable cliffs.

Throughout the traitor lines, the Sons of Horus fought with bitter hatred in their hearts, First Captain Abaddon leading the Warmaster's finest in battle, his wrath terrible to behold. He killed with unremitting savagery, while Horus Aximand fought beside him, his blows mechanical and forlorn as his haunted eyes took in the scale of the slaughter.

In the centre of the traitor line, the Emperor's Children fought with unremitting cruelty, its warriors howling with savage glee as they killed their former brothers. Unnatural horrors of mutilation and degradation were visited upon the living and the dead as Fulgrim's Legion repulsed every attack, though their primarch was yet to be seen.

Bizarrely clad warriors in Mark IV plate draped in stretched skin cavorted in the midst of the deadliest combats, fighting without helmets, their jaws wired open as they unleashed a hideous screaming. They bore unknown weaponry and fired echoing blasts of atonal harmonics that ripped bloody canyons in the massed ranks of the Iron Hands. Great pipes and loudspeakers fixed to their armour amplified the screaming vibrations of their killing music, and deafening sound waves tore apart warriors and armoured vehicles.

As the bulk of the heavier equipment was landed behind the ferocious battle, more and more explosions erupted in the traitors' lines, and even Angron and Mortarion were forced to pull back out of range of the loyalist artillery. In the centre of the battle, Ferrus Manus pushed ever onwards, his Iron Hands pushing deeper and deeper into the heart of the enemy defences as they sought to punish the traitors and unleash their wrath on the Emperor's Children.

Thousands were dying every minute, the slaughter terrible to behold. Blood ran in rivers down the slopes of the Urgall Depression, carving thick, sticky runnels in the dark sand. Such destruction had never yet been concentrated in such a horrifically confined space, enough martial power to conquer an entire planetary system having been unleashed in a line less than twenty kilometres wide.

Entire squadrons of armoured vehicles fought to reach the front lines, but the press of armoured bodies was so thick that their commanders were frustrated in their desire to crush the traitors beneath their armoured bulk. Firing lines of Land Raiders formed and collimated lines of ruby laser fire stabbed towards the fortress and the leviathan-like form of the Dies Irae.

Void shields flickered and, realising the danger, the monstrous Titan switched its fire from the infantry to the armour. Rippling blasts of plasma energy sawed along the line of tanks, and a dozen exploded as the white heat of fire torched their energy magazines.

The slaughter continued unabated, on a scale never before seen, with neither side able to press home their advantages. The traitors were well dug in and had defensible positions, but the loyalists had landed virtually directly on top of them with vast numerical superiority.

The bloodletting was a truly horrific sight as warriors who had once sworn great oaths of loyalty to one another fought their brothers with nothing but hatred in their hearts. No Legion fared well in the slaughter, the scale of the fighting rendering tactics meaningless as the two armies battered each other bloody in a remorseless conflict that threatened to destroy them all.

Julius danced through the combat, the sights and sounds of the killing causing rushes of physical pleasure to spasm through his body as he fought with savage joy. His armour was dented and gashed in a dozen places, but the wounds he had suffered only spurred his frenetic killing dance to greater heights. In preparation for the fighting, he had repainted its every surface in a riot of colours that stimulated his freshly reborn vision.

He had similarly enhanced his weapons, and the looks of horror and disgust that accompanied his every killing blow fired his senses.

'Look upon me and realise the greyness of your lives!' he screamed as he fought, delirious with slaughter. He had long since discarded his helmet to better experience the chaos of the battle, the roar of guns, the buzz of swords through flesh, the explosions and the vividness of shell traceries across the heavens.

He ached to have Fulgrim next to him in this most exquisite of battles, but the Warmaster had plans enough for the Primarch of the Emperor's Children. A petulant frown creased Julius's ecstatic features, and he spun to deliver a perfectly aimed decapitating strike at a dark armoured Iron Hands warrior. Horus and his plans! Where amongst these plans was the time to enjoy the spoils of victory? The powers and desires awakened within him by the Maraviglia were for the using. To deny them was to deny one's own nature.

Julius swept up the helmet he had just cut from his enemy and plucked the head from within, taking a moment to savour the stink of the blood and scorched flesh where his blade had cauterised it.

'We were brothers once!' he cried with mock gravitas. 'But now you are dead!'

He leaned in and kissed the cold lips of the Iron Hand, laughing as he hurled it high into the air, where it was ripped apart in the near constant hail of bolts. Whooping howls of manic laughter and thrumming bass explosions swept towards him, and he threw himself flat as a killing wave of sound roared overhead. The musical wave was excruciatingly loud, but Julius screamed in pleasure as the noise sluiced through his flesh.

Julius rolled to his feet in time to see a burnished group of Terminators lumbering towards him, and he grinned in feral glee as he saw they were led by Gabriel Santar, the first captain's markings on his armour standing out like a beacon in the darkness.

A whooshing roar of clashing noise tore a great furrow in the ground beside him and blasted upwards from the black sand like a volcanic eruption. Behind him, Julius saw the flesh-wrapped form of Marius, and roared with the pleasure of seeing his fellow captain alive and fighting.

Marius Vairosean had embellished his armour with jagged iron spikes, and had torn the skin from the dead of La Venice to decorate its blood-slathered plates. Like Julius, he had not walked away from the Maraviglia without alteration, the monstrous distension of his jaws locking his mouth open in a constant, howling scream. Where his ears had once been were two great gashes carved in his flesh, and his eyes were stitched open, forever prevented from closing.