Prisoners screamed and Iron Warriors bellowed commands at the mutant herders as more warriors in power armour emerged from hiding now that the trap was sprung. Bolter shells stitched an explosive path through the prisoners, blood and screams filling the air as they died. More missiles shot out and exploded against the bunkers, and Uriel heard the crack of stonework collapsing under the onslaught.

'Let's go!' shouted Uriel, activating his sword and charging from cover towards the panicked column of prisoners. Pasanius was quick to follow him, a blue flame leaping to life on the end of his weapon.

Uriel saw an Iron Warrior clubbing a prisoner with the butt of his gun and aimed his charge towards him. The warrior was a full head and shoulders above Uriel, his armour spiked and daubed with unclean symbols. A pair of curved and looping horns sprouted from his helmet and he carried a brutal sword with screaming, serrated teeth. He spun, hearing Uriel's wild charge and raised his weapon, but it was already too late. Uriel slashed his sword through the Iron Warrior's breastplate, drawing a spray of black blood and a roar of pain from his foe.

Pasanius sprayed a sheet of flame across a second Iron Warrior, one with mechanised, snapping claws for hands and an explosion ripped through the prisoners as a fuel-filled tank on the Chaos Marine's back detonated.

Uriel heard the roar of bolter fire from above, seeing scores of warriors in different coloured power armour charging from their concealment. He swayed aside as the Iron Warrior swung his sword in a graceless arc meant to behead him and slashed his sword around at his flank, cutting a full handspan into his armour. More missiles speared out from the spires, slamming into the towering daemon head and rocking it back. Thick cable stays snapped and whipped around in slashing arcs as the daemon tower roared.

Heavy calibre shells ripped from its mouth, tearing great gouges in the earth as they sprayed through the camp, striking friend and foe alike. The mutants in rubberised body suits jabbed the prisoners back to the camp, drawing blood and piteous cries from their wretched charges.

The Iron Warrior roared in anger, stepping forward to smash his fist against Uriel's chest. His strength was phenomenal, even for one genetically engineered to be stronger, and Uriel was hurled back, skidding through the ash as his attacker raised his sword two-handed to deliver the deathblow. He drew his pistol and squeezed off two shells, both ricocheting from the Iron Warrior's armour.

'Now you die, renegade!' bellowed the traitor.

Uriel rolled aside as the screaming sword hacked into the ground, kicking out at the Iron Warrior's kneecap. He roared as he struck, putting his entire strength behind the blow, feeling his foe's armour splinter and the knee shatter into fragments. The Iron Warrior howled and dropped to the ground. Uriel didn't give him a chance to recover and stepped in, driving his sword clean through the Iron Warrior's chest.

The warrior seized his neck and chuckled, a throaty death rasp, and Uriel felt the immense strength in the grip. He twisted the blade, spurts of blood spraying his hands as the wound tore wider. The Iron Warrior's grip on his neck tightened and he heard a joint in his gorget pop and crack as his dying foe sought to choke the life from him. Uriel slammed his fist into the side of the warrior's helmet again and again, pounding his skull to destruction until he finally released his grip.

Uriel staggered back from the dead Iron Warrior, seeing the Space Marines storming through the open gateway in the razorwire fence. The bunkers were smoking ruins, their interiors like abattoirs. Gunfire blasted from the daemonic tower, ripping through the ranks of the attacking Space Marines. Some fell, but most picked themselves up before ducking into whatever cover they could find. Mutants fled before the wrath of the attackers, but they were cut down without mercy, hacked to death with swords or beaten to death with armoured gauntlets.

The fire from the tower was punishing the attackers and as its fiery gaze swept across the plateau, Uriel had a sickening sensation that it saw him, saw him and recognised him…

Even as he watched, he saw a warrior in midnight black power armour leap from a spire of rock to one side of the camp. A searing fire erupted from his back and Uriel saw the warrior was wearing a jump pack. Smoke and flames fired from its vents, propelling the warrior through the air to land on the head of the daemon tower. Flames burst from its eyes and the tower shook violently, but whether that was in response to the Space Marine landing on it or the daemon's own fury, it was impossible to tell.

The warrior slashed at the daemonic head with lightning sheathed claws, crackling arcs of blue energy flaring where he struck, before swinging one-handed from the side of the head and clamping something to its side. The tower shook violently, as though seeking to dislodge its attacker, but the dark armoured warrior drove his lightning claws into the daemon head and hung on. He swung around the tower, slashing at the thick cables that held it in place before bracing his feet against its cheek and pushing off. His jump jets fired as the melta charge he had placed on the daemon head detonated and he flew clear on the bow wave of an explosion that vaporised the top of the tower in a pluming mushroom cloud of incandescent energy.

With a shrieking roar, the tower swayed drunkenly, the few remaining cable stays twanging loudly as they pulled taut before snapping with the crack of a gunshot. The tower toppled majestically, crashing through the corrugated tin roof of the nearest warehouse and sending up plumes of dust and smoke.

Gunfire sounded sporadically from the camp as the last of the mutant labourers were rounded up and killed, and Uriel let out a deep breath as he saw that the battle was over.

He dragged his sword from the chest of the body before him, looking around to see an Iron Warrior on his knees, blood flooding down his breastplate as Pasanius slashed at him with his own chainblade. Both his arms had been hacked off and his belly had spilled its contents across the dark earth.

The fight was gone from the Iron Warrior, but still Pasanius took his measure of vengeance from him. A mob of Space Marines had the last Iron Warrior surrounded and shot him to death without mercy, their bolts penetrating his torn armour and exploding wetly within his flesh.

Only now, with the battle over, did Uriel really pay close attention to the armour of the Space Marines he had fought alongside. No more than two or three were alike in colour or design, and each bore testament to many hard fights, with ancient battle scars hastily and imperfectly repaired with crude grafts and filler. Almost all bore a different Chapter symbol on their shoulder guards and many had painted over them with jagged red saltires.

Wailing slaves squatted in their folds of flesh or cradled each other in their misery. Uriel ran over to Pasanius as he continued to hack the fallen Iron Warrior into pieces.

'Pasanius!' shouted Uriel.

He grabbed Pasanius's arm as he drew back for another blow. 'Pasanius, he is dead!'

Pasanius's head snapped round, his eyes ablaze with fury. For the briefest second, Uriel feared that something terrible had possessed his friend, then the killing light went out of him and he dropped the Iron Warrior's weapon and let out a deep, shuddering breath. The sergeant dropped to his knees, his face ashen at the fury he had unleashed.

'Your comrade's anger does him credit,' said a voice behind Uriel and he turned to see the warrior in black who had destroyed the tower. His armour was a far cry from the usual gleaming brilliance of a Space Marine's power armour, being ravaged with dents, scars and patches. Hot vapours vented at his shoulders from the nozzles of his jump pack, and a white symbol - a bird of prey of some kind - had been painted over with a jagged red cross. His helmet bore a similar symbol across his visor.