His eyes blazed and Uriel could see the beast he had become was eager to do them more harm, but before he could enact it, his entire body shuddered and the daemon-thing Onyx had become retreated back into his flesh, the golden swords writhing and sliding back into his hands.
Even as Uriel watched, Onyx's original form was restored before his eyes.
Onyx let out a long breath and dropped to one knee, but before any of the warrior band could take advantage of his momentary vulnerability, the undulating forms of the Exuviae roared like black tidal waves and bore down upon them. Uriel struggled to rise, but the bubbling, animated pollutants swept over him, pinning his arms and holding him fast within their grip.
Dull, mindless eyes ruptured from the toxin-flecked matter, blinking idiotically at him and he heard the repulsed cries of the surviving Space Marines as the Exuviae swallowed them in their stinking, foetid embrace.
With Onyx leading the way through the interior of Khalan-Ghol, the delirious architecture seemed to resolve itself in response to his very presence. Where the chaotic nature of its plan had led Uriel and his battle-brothers a merry dance through its shadow-haunted streets, it eased the path of the daemonic creature and his shambling, slithering following. The Exuviae roiled along the cobbled streets with a grotesque, rippling motion, bearing their immobile charges within their odious, fluid bodies.
Only Uriel, Pasanius, Vaanes, Seraphys, Leonid, Ellard and nine other Space Marines had survived to reach this far within the fortress, but Uriel knew that so long as he drew breath he could not forgo his death oath. The soot-stained thoroughfares of the fortress soon fell away to reveal their ultimate destination: the centre of the fortress and the great tower of iron.
Whether it had been a trick of perspective or the illusory power of Chaos, Uriel did not know, but he was shocked speechless by its sheer immensity. Its summit was lost to sight beyond the writhing purple clouds above and it was impossible to see the entirety of its width. Twisting, crooked towers sprouted from its sides, overhanging forges spewed thick toxins into the air, swooping winged things clustered around dark rookeries and evil lightning crackled from slitted windows. A high wall surrounded the base of the tower, its ramparts thick with Iron Warriors and gun turrets.
A huge gate of black iron with a tall, armoured barbican to either side defended the entrance to the tower and as Onyx led them towards it, the dread portal swung open with a scream of deathly anguish. The Exuviae carried them through the dark gate, and as they were borne along the passageway, Uriel saw scalding steam gusting from the spiked murder holes in the roof.
Emerging from the oppression of the gateway, Uriel gaped in dark wonderment as he saw that the tower did not sit upon the rock of the mountain at all, but was impossibly suspended over a giant void that mirrored the dead sky above on hundreds of immense chains. Each link was as thick as the columns that supported the great portico before the Temple of Correction and as they were carried towards a bridge, Uriel saw that the tower also plunged deep into the void for thousands of metres.
'Emperor protect us…' breathed Uriel.
'You waste your breath,' said Onyx. 'You think he has any power in this place?'
Uriel disdained to reply, unwilling to further bandy words with one touched by the fell powers of the immaterium. A long basalt slab spanned the void, its surface worn smooth by the passage of uncounted marching feet, leading to an enormous gateway that pierced the tower itself. As they crossed the bridge, Uriel saw that it was fashioned from some deathly material, hissing and spitting as though fresh from the forge. Its scale was colossal: entire regiments would be able to march through and the tallest of Titans could pass beneath it without fear.
Onyx led them towards the gate, a smaller, rivet-studded postern granting them access to the tower's echoing interior. Uriel felt the power of ages past within the tower and its ancient malice was a potent breath on the air.
'Khalan-Ghol,' said Onyx proudly. 'The power and majesty of a living god helped forge this fortress, shaping it into a form pleasing to him, unfettered by any of the laws of nature.'
'It is an abomination!' snarled Pasanius.
'No,' said the daemonic symbiote. 'It is the future.'
The interior of the tower was no less horrifying than its exterior - vast dusty halls of bronze statues, huge, sweating forges that spat sparks and orange rivers of metal. A parching, stifling heat infused the tower, black moisture dripping from the shadowed vaults of the ceiling. Uriel could hear distant screams and heavy hammer-blows far below, louder and more powerful than he had heard thus far on Medrengard.
Crawling shadows, perhaps more of the Exuviae, lurked in the high cloisters, though the most numerous inhabitants of the tower appeared to be figures swathed in black robes, walking with a wheezing mechanical gait.
Red augmetic eyes scanned them with interest as Onyx led his coterie of Exuviae deeper into the tower, clicking brass limbs grasping towards them with a hissing hunger. Warped cog symbols combined with the eight-pointed star of Chaos were burned into their robes and gurgling algorithmic voices clicked between them as they tended to vast, dusty machines whose purpose was lost on Uriel.
As they passed a hulking, bronze construction with pumping, greased pistons and an armature-mounted pict-slate, a huge, hissing monster stepped from the shadow of the great machine to bar their way.
Onyx stiffened as the black-robed creature shuffled painfully into a pool of light and Uriel felt a creeping horror scrape its way up his spine at the sight of it. It moved awkwardly on six, spider-like legs of riveted iron, its body braced within an oil-stained exo-skeleton at its cenue. Where its flesh was exposed, Uriel could see that it was withered and dead, a patchwork of sutures running along raised ridges of bone. Its head was heavy and hung low on its shoulders, brass rods piercing the width of its skull and scaffolded by a cage of brass bolted to its temples. Its hooded face was a loathsome, parchment-coloured skull, the lower half gleaming metal and flensed of skin, its eyes replaced with whirring mechanical optical feeds.
Myriad transparent tubes pierced its flesh, running in gurgling loops around its body and hissing valves released noxious gusts as its chest heaved with the effort of breath. It reached forward to lift Uriel with long, augmetic arms, bulky with scalpels, drills and blowtorches.
Onyx stepped in front of the creature, his claws unsheathing.
'No,' he said. 'These ones are for the master of Khalan-Ghol.'
The beast hissed in anger, its clawed hands snapping in frustration and its drill bits whirring dangerously close to Onyx's head. It reached down to push Onyx out of its way, but the black-armoured warrior refused to be moved.
'I said no,' he repeated. 'It may be that the Savage Morticians will have them in time, but that time is not now.'
The creature appeared to consider this for a moment, before its hideous skull face nodded and it retreated into the shadow of the machine once more.
Onyx watched it go and, while his attention was elsewhere, Uriel struggled within the stinking prison of the beast that bore him, Pasanius and Vaanes, but it was no use, they were held utterly immobile. At last, sure the Savage Mortician was not waiting in ambush, Onyx sheathed his claws and led the Exuviae bearing his prisoners onwards.
Uriel's frustration grew with every darkened hall they traversed and every impossibly angled staircase they climbed or descended, unable to move so much as a single muscle. The maddening sound of hammering grew louder the further they travelled and the same emerald light that permeated the city beyond the tower grew brighter as their journey led them from passages and chambers raised by the hands of men into a vast fiery cavern edged with great steam-venting pistons.