The sight of it stunned Zahariel. It etched itself indelibly into his brain. This was worse by far than the horrors he'd witnessed on Sarosh. There, too, he had been deep beneath the ground, surrounded by death and corruption, but on Sarosh, the vile, jellylike creature they'd faced had been clearly born of the shifting madness of the warp. This taint, this evil that suffused every root and vine, was inextricably part of Caliban itself.

ELEVEN

Conversations by Starlight

The attack was so fast that it momentarily took Nemiel off-guard. In the space of a single heartbeat the Praetorians erupted into a blur of deadly motion, bringing their weapons to bear and charging across the last few metres between themselves and the Astartes. Multi-barrel slug throwers pounded at the Dark Angels, the explosive shells bursting in a series of sharp flashes across the ceramite surfaces of their armour. The warriors staggered under the hail of shells, blood spraying from wounds to their arms, torsos and legs. Urgent red telltales flashed on Nemiel's helmet display; pain flared across his chest, and his arms suddenly felt twice as heavy. A Praetorian shell had likely cut a bundle of synthetic muscle fibres beneath his breastplate.

Brother-Sergeant Kohl was the first to respond. There was no time for questions or recriminations; the Praetorians were descending on them with the speed of a thunderbolt, brandishing power claws and blazing shock mauls that would make a mockery of their Crusader-pattern armour. The Terran staggered backward under a punishing barrage of explosive shells, roaring a curse in some forgotten tongue and returning fire with his bolt pistol. The shells struck one of the charging skitarii in the chest and head, flattening against the augmented warrior's armour plates without inflicting serious damage, but the gesture of resistance was enough to shock the rest of the squad back into action.

Bolters hammered at the charging Praetorians, slowing their advance by sheer weight of fire. Blood and other fluids spurted from minor wounds; spatters of liquid hissed into steam where it struck the Praetorians' super-charged bionics. Nemiel smelled the acrid reek of adrenal compounds and hormone agitators.

Off to Nemiel's right there was a shriek of superheated air as Brother Marthes shot one of the oncoming skitarii point-blank with his meltagun. The anti-tank weapon blew the Praetorian apart in a shower of sparks and charred bits of flesh.

The Praetorian rushing at Nemiel was a massive brute that seemed more machine than man; a composition of bionic joints, synthetic musculature, adrenal shunts and pitted armour plating. His head was encased in a faceless metal shell, studded with multi-spectrum auspex nodes in place of ears, nose and mouth. His breastplate was decorated - if that was the word - with bar-code emblems and small plaques of glittering, iridescent metal. Perhaps he was a champion of sorts, or the leader of the detachment; Nemiel couldn't be sure. The Praetorian's left hand had been replaced by a huge, three-fingered power claw, its curved edges plated with adamantium and sharpened to a mirror-sheen. The warrior lunged at Nemiel with stunning speed, swiping the claw at his face.

He knew better than to try and parry something so large, the power claw could easily knock his crozius aside - or worse, snap it cleanly in two. Instead, he ducked, allowing the Praetorian's swing to pass harmlessly over his head, and smashed his staff into the warrior's elbow. The power field of the crozius struck the bionic joint and fused it with a flash of actinic light, but the Praetorian scarcely seemed to notice. The huge warrior spun on his left heel and brought his right elbow back to smash into Nemiel's forehead.

Ceramite cracked loudly in Nemiel's ears, and the impact hurled him off his feet. He landed squarely on his back, his helmet readouts crackling with washes of static. Without thinking, he fired a quick burst in the Praetorian's direction, and was rewarded with the sound of shells striking the warrior's armour plate. The skitarii was just a blurry shape on the helmet's damaged optical systems, fading in and out of existence like a monstrous ghost. The Praetorian moved closer, his claw arm reaching for Nemiel's right leg.

A flash of light and another howl of tortured air swept over Nemiel. Marthes's shot vaporised the Praetorian's claw arm at the elbow and blistered the warrior's armoured shoulders and chest. The skitarii reeled backwards, his auto-senses momentarily overloaded.

Nemiel dropped his pistol and clawed at his helmet release. He popped the catches with nimble fingers and tore the damaged helm from his head, blinking in the dim, red light of Diamat's distant sun. A wild melee was raging all around him as his battle brothers fought against the heavily-armed Praetorians. Brother Yung was down, his breastplate torn like paper and stained with blood. Techmarine Askelon had another of the Praetorians by the throat, lifting the brute off the ground with his servo arm and crushing the skitarii's metal-sheathed spine.

He quickly turned his focus back to the one-armed Praetorian just a few metres away. The augmented warrior was in a crouch, the air shimmering around his scorched armour, his body eerily still as he reset his auspex nodes. Nemiel snatched up his bolt pistol and took careful aim, preparing to put a round through the Praetorian's throat.

Suddenly a strange, trumpeting blurt of binaric code cut like a knife through the sounds of battle, and the Praetorians practically recoiled from the Dark Angels. They retreated a dozen steps and lowered their weapon arms, their chests heaving from exertion and the combat drugs that were boiling in their veins. The Astartes paused, their weapons trained on their adversaries. Kohl looked to Nemiel for instructions.

But the Redemptor's attention was focused on a large force of armoured skitarii rushing down the roadway from the northeast. They were led by a tall, hooded figure clad in the crimson robes of the Mechanicum, riding atop a humming suspensor disk.

Nemiel rose swiftly to his feet as the figure glided closer. 'What is the meaning of this, magos?' he snarled, his choler nearly overwhelming him.

'Error. Improper threat parameters. Misidentification,' the magos blurted in High Gothic. The voice was harsh and atonal, the words strangely inflected but recognizable. The magos paused, raising a hand that glittered in the rust-coloured sunlight. 'Apologies,' he continued, his synthetic voice more carefully modulated now. 'Grave apologies to you and your squad, noble Astartes. The skitarii were in seek-and-destroy mode, searching for enemy troops that had penetrated the complex. Your appearance on Diamat is… unexpected. I was unable to override the Praetorians' engagement protocols until it was too late.'

'I see,' Nemiel said curtly. So it's our fault for rushing here to protect you, he thought. He glanced over at Brother-Sergeant Kohl and guessed from the Terran's belligerent pose that he was thinking much the same thing. 'How is Brother Yung?'

'Comatose,' Kohl growled. 'His injuries are grave.'

'Let us conduct him to the forge's apothecarium,' the magos said at once. 'We will repair his body and mend his damaged armour.'

For some reason, the magos's offer took Nemiel aback. 'That won't be required,' he said quickly. 'We will conduct him back to our ship when the battle is done, and let our brothers tend to him.' He studied the hooded figure warily. 'I am Brother-Redemptor Nemiel, of the Emperor's First Legion. Who are you?'

The magos laid one metal hand atop the other and bowed from the waist. 'I am Archoi, magos of the Forge and former servant of the Arch-Magos Vertullus,' he said.