Unseen currents of aetheric energy sliced into the Space Wolves, blocking neural transmitters, redirecting electrical impulses in the brain and rapidly deoxygenating the blood flowing from their lungs. The effect was instantaneous.

The Space Wolves’ push faltered as their bodies rebelled. Limbs spasmed, heart muscles fibrillated and warriors lost all physical autonomy, jerking like the maddened dolls of a demented puppeteer. Ahriman watched as Amlodhi Skarssen dropped to one knee, his shield falling from nerveless fingers as his body refused to answer his demands.

The Wolf Lord’s teeth gnashed together, bloody foam spilling from the mouthpiece of his mask. Space Wolves thrashed in bone-cracking agony as their nervous systems were flooded with conflicting neural impulses. Ahriman despaired of the relish Hathor Maat took in this wanton display of power. The Pavoni had a reputation for venality and spite, but this was sickening.

“Stop this!” cried Ahriman, unable to contain his wrath. He ran forward and gripped Hathor Maat’s arm, twisting him around to face him. “Enough! You are killing them!”

Ahriman sent a blast of white noise into Hathor Maat’s aura, and the captain of the 3rd Fellowship flinched.

“What are you doing?” demanded Hathor Maat.

“Stopping this,” said Ahriman. “Release them.”

Hathor Maat stared at him, and then glanced at Magnus. Ahriman leaned in and gripped him by the edge of his pauldrons.

“Do it!” shouted Ahriman. “Stop it now!”

“It’s done,” snapped Hathor Maat, pushing Ahriman away.

Ahriman turned back to the Space Wolves, letting out a shuddering breath as the energies of the Pavoni diminished. The grey-armoured warriors lay on the causeway, their charge broken, their impetus lost. Amlodhi Skarssen struggled to his feet, battling against rogue impulses tearing through his body. Skarssen’s eyes were filled with blood, and his entire body shook with the effort of standing before his enemies.

“I… Know… You,” hissed Skarssen, fighting for every word. “All… Of… You.”

“I told you to stop this!” cried Ahriman, rounding on Hathor Maat.

“And so I did,” protested Hathor Maat. “I swear.”

Ahriman felt a ferocious surge of power beside him and saw Hastar shaking as hard as Amlodhi Skarssen. Ahriman reached into his aura and felt a hot pulse of terror mixed with aberrant energies.

With a sickening sense of horrified recognition, he understood what was happening.

Hathor Maat saw it at the same time, and they barrelled into Hastar, knocking him to the ground as he began thrashing in the grip of a violent seizure.

“Hold him down!” shouted Ahriman, tearing at the pressure seals of Hastar’s gorget.

“Please, no,” begged Hathor Maat. “Hold on, Hastar! Fight it!”

Ahriman tore off the warrior’s helmet and threw it aside, looking down at something he had hoped and thought never to see again.

Hastar’s flesh seethed with ambition, writhing and twisting in unnatural ways, the meat and bone of his skull bulging with fluid growth. The warrior’s eyes were terrified, uncomprehending orbs filled with red light, like coals from a smouldering forge.

“Help me,” gasped Hastar.

“Flesh-change!” shouted Ahriman.

He fought to hold Hastar’s body down, but the changes wracking his body were as apocalyptic as they were catastrophic. His armour buckled as the body beneath it expanded so furiously and violently that the breastplate cracked down its centreline, the flesh beneath alive with change. Energised veins of electricity threaded his pallid flesh, sheened with glittering hoar-light sweating from the agonised warrior’s suddenly malleable flesh.

Hastar screamed, and Ahriman’s grip slackened as the horror of Ohrmuzd’s death surged from the locked room of his memory. Hastar threw them off, his expanding body swollen with grotesquely misshapen musculature, encrusted growths, mutant appendages and slithering ropes of wet matter.

With the gurgle of wet meat and the crack of malformed bones, Hastar’s body was suddenly upright, though any semblance of limbs was impossible to pick out in his erupting flesh. Swelling bulk and crackling energy patterns writhed across his flesh, and his screams turned to bubbling gibbers of maniacal laughter.

“Kill it!” shouted a voice, but Ahriman couldn’t tell whose.

“No!” he shouted, though he knew it was futile. “It’s still Hastar. He’s one of us!”

The Thousand Sons scattered from Hastar’s terrible new form, horrified and terrified in equal measure. This was their greatest fear returned to haunt them, a horror from their past long thought buried.

Unchained energies whipped from Hastar’s appendages, his torso and legs fused in a rippling trunk of glowing, protean flesh. Frills of half-formed membranes flapped in unseen winds, and a hateful laughter bubbled up from vestigial mouths that erupted all across his flesh. Hundreds of distended eyes, compound like an insect’s, slitted like a reptile’s or milky with multiple pupils boiled to life and popped with wet slurps every second. No part of the creature’s anatomy was fixed for more than a moment.

A dreadful, wracking sickness seized Ahriman, as though his innards were rebelling against their fixed shapes, his entire body trembling with desire for a new form.

“No!” cried Ahriman through gritted teeth. “Not again… I will not… succumb! I am Astartes, a loyal servant of the Supreme Master of Mankind. I will not fall.”

All around him, the Thousand Sons were on their knees or backs, fighting the virulent power of transformation as it spread from Hastar with the speed of the Life-Eater virus. Unless this power was dispelled, they would all fall prey to the spontaneous mutations that had once nearly ended their Legion.

“I survived before,” snarled Ahriman, clenching his fists. “I will survive again.”

Determination gave him strength, and he flexed his mind into the Enumerations, distancing himself from the pain and his trembling flesh. With every sphere he attained, his mastery of his corporeal form increased until he could open his eyes once more.

His every muscle ached, but he was still Ahzek Ahriman, of sound mind and body. He glanced over his shoulder, seeing the Space Wolves coming to their senses on the causeway. Either they were beyond the reach of these transformative energies or they were immune to its effects. The damage the Pavoni had wreaked upon their nervous systems was coming undone, and Amlodhi Skarssen took faltering steps towards the Thousand Sons, his axe unsheathed.

A surging wave of power erupted behind Ahriman and he rolled onto his side in time to see Magnus the Red step towards the hideously transformed Hastar. Unchecked energy had destroyed the warrior of the Pavoni, but it empowered Magnus. The creature Hastar had become reached out to Magnus, as though to embrace him, and the primarch opened his arms to receive him with forgiveness and mercy.

A thunderous bang sounded and Hastar’s body exploded as a single, explosive round detonated within his chest. Silence descended, and Ahriman distinctly heard the heavy tinkof a monstrous brass casing striking the ground.

Ahriman followed the trajectory the shell had taken, tracing a smoking line back to a giant pistol gripped in the fist of a towering giant clad in grey ceramite and thick wolf pelts.

The Wolf King had come.

A faded poem, last read in a dusty archive in the Merican dustbowl, leapt unbidden to Ahriman’s mind. Supposedly transcribed from a commemorative monument, it marked the beginning of an ancient and awesomely destructive war:

By the rude bridge that arched the flood,

Their flag to April’s breeze unfurled;

Here once the embattled farmers stood,