Horus watched the swirling, noxious clouds enveloping the planet below.

All it would take was a single spark.

He imagined the planet as the frayed end of a fuse, a fuse that would ignite the galaxy in a searing conflagration and would lead to an inexorable conclusion on Terra.

'Order the guns to fire,’ said Horus, his voice cold. 'Let the galaxy burn!'

'EMPEROR PRESERVE US,' whispered Moderati Cassar, unable to hide his horror and not caring who heard him. The miasma of rancid, putrid gasses still hung thickly around the Titan and he could only dimly see the trenches again, along with the Death Guard emerging from the bunkers. Shortly after the order to seal the Titan had been given, the Death Guard had taken cover, clearly in receipt of the same order as the Dies Irae.

The Isstvanians had received no such order. The Death Guard's withdrawal had drawn the Isstvan-ian soldiers forwards and they had borne the full brunt of the bio-weapon.

Masses of mucus-like flesh choked the trenches, half-formed human corpses looming from them, faces melted and rot-bloated bodies split open. Thousands upon thousands of Isstvanians lay in rotting heaps and thick streams of sluggish black corruption ran the length of the trenches.

Beyond the battlefield, death had consumed the forests that lay just outside the Choral City's limits, now resembling endless graveyards of blackened trunks, like scorched skeletal hands. The earth beneath was saturated with biological death and the air was thick with foul gasses released by the oceans of decaying matter.

'Report,’ said Princeps Turnet, re-entering the cockpit from the Titan's main dorsal cavity.

'We're sealed,’ said Moderati Aruken on the other side of the bridge. 'The crew's fine and I have a zero reading of contaminants,’

'The virus has burned itself out,’ said Turnet. 'Cas-sar, what's out there?'

Cassar took a moment to gather his thoughts, still struggling with the hideous magnitude of death that he couldn't have even imagined had he not seen it through the eyes of the Dies Irae.

'The Isstvanians are... gone,’ he said. He peered through the swirling clouds of gas at the mass of the city to one side of the Titan. 'All of them,’

The Death Guard?'

Cassar looked closer, seeing segments of gun-metal armour partially buried in gory chokepoints, marking where Astartes had fallen.

'Some of them were caught out there,’ he said. 'A lot of them are dead, but the order must have got to most of them in time,’

The order?'

Yes, princeps. The order to take cover,’

Turnet peered through the Titan's eye on Aruken's side of the bridge, seeing Death Guard warriors through the greenish haze securing the trenches around their bunkers and treading through the foul remains of the Isstvanians.

'Damn,’ said Turnet.

We are blessed,’ said Cassar. They could so easily have been-'

Watch your mouth, Moderati! That religious filth is a crime by the order of-'

Tumet's voice cut off as movement caught his eyes.

Cassar followed his gaze in time to see the clouds of gas lit up by a brilliant beam of light as a blazing lance strike slashed through the clouds of noxious, highly flammable gasses.

ALL IT TOOK was a single spark.

An entire planet's worth of decaying matter wreathed the atmosphere of Isstvan III in a thick shawl of combustible gasses. The lance strike from the Vengeful Spirit burned through the upper

atmosphere into the choking miasma and its searing beam ignited the gas with a dull whoosh that seemed to suck the oxygen from the air.

In a second, the air itself caught light, ripping across the landscape in a howling maelstrom of fire and noise. Entire continents were laid bare, their landscapes seared to bare rock, their decayed populations vaporised in seconds as winds of fire swept across their surfaces in a deadly gale of blazing destruction.

Cities exploded as gas lines went up, blazing towers of fire whipping madly in the deadly firestorm. Nothing could survive and flesh, stone and metal were vitrified or melted in the unimaginable temperatures. Entire sprawls of buildings collapsed, the bodies of their former occupants reduced to ashen waste on the wind, palaces of marble and industrial heartlands destroyed in gigantic mushroom clouds as the storm of destruction swept around Isstvan III with relentless, mindless destruction until it seemed as though the entire globe was ablaze.

Those Astartes who had survived the viral attack found themselves consumed in flames as they desperately sought to find cover once more.

But against this firestorm there could be no cover for those who had dared to brave the elements.

By the time the echoes of the recoil had faded on the Warmaster's flagship, billions had died on Isstvan III.

* Ф *

MODERATI CASSAR HUNG on for dear life as the tempestuous firestorm raged around the Dies Irae. The colossal Titan swayed like a reed in the wind, and he just hoped that the new stabilising gyros the Mechanicum had installed held firm in the face of the onslaught.

Across from him, Aruken gripped the rails surrounding his chair with white knuckled hands, staring in awed terror at the blazing vortices spinning beyond the command bridge.

'Emperor save us. Emperor save us. Emperor save us,’ he whispered over and over as the flames billowed and surged for what seemed like an eternity. The heat in the command bridge was intolerable since the coolant units had been shut down when the Titan was sealed off from the outside world.

Like a gigantic pressure cooker, the temperature inside the Titan climbed rapidly until Cassar felt as if he could no longer draw breath without searing the interior of his lungs. He closed his eyes and saw the ghostly green scroll of data flash through his retinas. Sweat poured from him in a torrent and he knew that this was it, this was how he would die: not in battle, not saying the Lectitio Divinitatus, but cooked to death inside his beloved Dies Irae.

He had lost track of how long they had been bathed in fire when the professional core of his mind saw that the temperature readings, which had been rising rapidly since the firestorm had hit, were beginning to flatten out. Cassar opened his eyes and saw the madly churning mass of flame through

the viewing bays of the Titan's head, but Пе also saw spots of sky, burned blue as the fire incinerated the last of the combustible gasses released by the dead of Isstvan.

'Temperature dropping,’ he said, amazed that they were still alive.

Aruken laughed as he too realised they were going to live.

Princeps Turnet slid back into his command chair and began bringing the Titan's systems back on line. Cassar slid back into his own chair, the leather soaking wet where his sweat had collected. He saw the readouts of the external surveyors come to life as the princeps once again opened their systems to the outside world. 'Systems check,’ ordered Turnet. Aruken nodded, mopping his sweat-streaked brow with his sleeve. "Weapons fine, though we'll need to watch our rate of fire, since they're already pretty hot,’

'Confirmed,’ said Cassar. We won't be able to fire the plasma weapons any time soon either. We'll probably blow our arm off if we try,’

'Understood,’ said Turnet. 'Initiate emergency coolant procedures. I want those guns ready to fire as soon as possible,’

Cassar nodded, though he was unsure as to the cause of the princeps's urgency. Surely there could be nothing out there that would have survived the firestorm? Certainly nothing that could threaten a Titan.

'Incoming!' called Aruken, and Cassar looked up to see a flock of black specks descending rapidly through the crystal sky, flying low towards the blackened ruins of the burned city.

'Aruken, track them,’ snapped Turnet.

'Gunships,’ said Aruken. They're heading for the centre of the city, what's left of the palace,’