The Astartes spread out through the fog, moving as swiftly as the boggy conditions allowed and following the source of the vox signal. Horus led from the front, a living god marching tall through the stinking quagmires and rank swamps of Davin's moon, untroubled by the noxious atmosphere. He disdained the wearing of a helmet, his superhuman physique easily able to withstand the airborne poisons.

Four blocks of Astartes marched, phalanx-like, into the mists, with each member of the Mournival leading nearly two hundred warriors. Behind them came the soldiers of the Imperial army, company after company of red-jacketed warriors with gleaming lasguns and silver tipped lances. Each man was equipped with rebreather apparatus after it was discovered that their mortal constitutions were unable to withstand the moon's toxic atmosphere. Initial landings of armour proved to be disastrous, as tanks sank into the marshland and dropships found themselves caught in the sucking mud.

Though the greatest of all the engines of war were those that emerged from the Mechanicum landers. Even the Astartes had paused in their advance to watch the descent of the three monstrously huge craft. Slowly dropping through the yellow skies in defiance of gravity like great primeval monoliths, the blackened hulks travelled on smoking pillars of fire as their colossal retros fought to slow them down. Even with such fiery deceleration, the ground shook with the hammerblow of their impacts, geysers of murky water thrown hundreds of metres into the air along with blinding clouds as the swamps flashed to steam. Massive hatches blew open and the motion resistant scaffolding fell away as the Titans of the Legio Mortis stepped from their landing craft and onto the moon's surface.

The Dies Irae led the Death's Head and Xestor's Sword, Warlord Titans with long, fluttering honour rolls hung from their armoured thorax. Each thunderous footstep of the mighty Titans sent Shockwaves through the swamps for kilometres in all directions, their bastion legs sinking several metres through the marshy ground to the bedrock beneath. Their steps churned huge gouts of mud and water, their appearance that of awesome gods of war come to smite the Warmaster's enemies beneath their mighty tread.

Loken watched the arrival of the Titans with a mixture of awe and unease: awe for the majesty of their colossal appearance, unease for the fact that the Warmaster felt it necessary to deploy such powerful engines of destruction.

The advance was slow going, trudging through clinging mud and stinking, brackish water, all the while unable to see much more than a few dozen metres. The thick fog banks deadened sound such that something close by might be inaudible while Loken could clearly hear the splash of warriors from Luc Sedirae's men, far to his right. Of course he couldn't see them through the yellow mist, so each company kept in regular vox contact to try and ensure they weren't separating.

Loken wasn't sure it was helping though. Strange groans and hisses, like the expelled breath of a corpse, bubbled from the ground and blurred shadow forms moved in the mist. Each time he raised his bolter to take aim in readiness, the mist would part and an armoured figure in the green of the Sons of Horus or the steel grey of the Word Bearers would be revealed. Erebus had led his warriors to Davin's moon in support of the Warmaster and Horus had welcomed their presence.

The mist gathered in thickness with unsettling speed, slowly swallowing them up until all Loken could see were warriors from his own company. They passed through a dark forest of leafless, dead trees, the bark glistening and wet looking. Loken paused to examine one, pressing his gauntlet against the tree's surface and grimacing as its bark sloughed off in wet chunks. Writhing maggots and burrowing creatures curled and wriggled within the rotten sapwood.

'These trees…' he said.

'What about them?' asked Vipus.

'I thought they were dead, but they're not.'

'No?'

'They're diseased. Rotten with it.'

Vipus shrugged and carried onwards, and once again Loken was struck by the certainty that something terrible had happened here. And looking at the diseased heart-wood of the tree, he wasn't sure that it was over. He wiped his stained gauntlet on his leg armour and set off after Vipus.

The eerily silent march continued through the fog and, assisted by the servo muscles of their armour, the Astartes quickly began to outpace the soldiers of the Imperial Army, who were finding the going much more difficult.

'Mournival,' said Loken over the inter-suit link. 'We need to slow our advance, we're leaving too big a gap between ourselves and the Army detachments.'

'Then they need to pick up the pace,' returned Abaddon. 'We don't have time to wait for lesser men. We're almost at the source of the vox.'

'Lesser men,' said Aximand. 'Be careful, Ezekyle, you're starting to sound a little like Eidolon now.'

'Eidolon? That fool would have come down here on his own to gain glory,' snarled Abaddon. 'I'll not be compared to him!'

'My apologies, Ezekyle. You're obviously nothing like him,' deadpanned Aximand.

Loken listened with amusement to his fellow Mournival's bantering, which, together with the quiet of Davin's moon began to reassure him that his concerns over their deployment here might be unfounded. He lifted his armoured boot from the swamp and took another step forward, this time feeling something crack under his step. Glancing down, he saw something round and greenish white bob upwards in the water.

Even without turning it over he could see it was a skull, the paleness of bone wreathed in necrotic strands of rotted flesh and muscle. A pair of shoulders rose from the depths behind it, the spinal column exposed beneath a layer of bloated green flesh.

Loken's lip curled in disgust as the decomposed corpse rolled onto its back, its sightless eye sockets filled with mud and weeds. Even as he saw the rotted cadaver, more bobbed to the surface, no doubt disturbed from their resting places on the bottom of the swamps by the footfalls of the Titans.

He called a halt and opened the link to his fellow commanders once again as yet more bodies, hundreds now, floated to the surface of the swamp. Grey and lifeless meat still clung to their bones and the imparts of the Titans' footfalls gave their dead limbs a horrid animation.

'This is Loken,' he said. 'I've found some bodies.'

'Are they Temba's men?' asked Horus.

'I can't tell, sir,' answered Loken. 'They're too badly decomposed. It's hard to tell. I'm checking now.'

He slung his bolter and leaned forwards, gripping the nearest corpse and lifting it from the water. Its bloated, rancid flesh was alive with wriggling motion, burrowing carrion insects and larvae nesting within it. Sure enough, mouldering scraps of a uniform hung from it and Loken wiped a smear of mud from its shoulder.

Barely legible beneath the scum and filth of the swamps he found a sewn patch bearing the number sixty-three emblazoned over the outline of a snarling wolfs head.

'Yes, 63rd Expedition,' confirmed Loken. 'They're Temba's, but I—'

Loken never finished the sentence as the bloated body suddenly reached up and fastened its bony fingers around his neck, its eyes filled with lambent green fire.

'Loken?' said Horus as the link was suddenly cut off. 'Loken?'

'Something amiss?' asked Torgaddon.

'I don't know yet, Tarik,' answered the Warmaster.

Suddenly the hard bangs of bolter fire and the whoosh of flame units could be heard from all around them.