'Engine kill,' said Princeps Cavalerio high up in the liquid depths of his amniotic tank.

The second Warhound fled at the sight of the larger engine, turning and sprinting for the support of its fellows like a bully confronted by a gang of his former victims.

It ran straight into the guns of Metallus Cebrenia and Arcadia Fortis, who caught it in a lethal crossfire that ripped away its voids and gutted it in a furious hurricane of turbos.

Behind the two jubilant engines, the Tempestus Warhounds, Vulpus Rex, Raptoria, Astrus Lux and the Warlord Tharsis Hastatus moved into position within the hab-blocks, ready to defend the Magma City against the might of Legio Mortis.

Surveying the smashed wreckage of the slain war machines, Princeps Cavalerio smiled.

he canted to his warriors.

From the Chamber of Vesta, high atop the silver pyramid in the centre of the Magma City, Adept Zeth read the inloaded data of the four destroyed Warhounds. The arrival of Tempestus two nights ago might have prompted her to believe in the providence of the Machine-God, but she knew she owed her city's continued survival to Princeps Cavalerio's honourable heart.

Even without the terrible threat of the Mortis Imperator, the Tempestus engines were dreadfully outnumbered and outgunned, yet still Cavalerio had come. Had he not been interred within an amniotic tank, she would have hugged him in a rare outburst of emotion.

The first blow had to be struck from ambush in an attempt to even the odds, and though Zeth keenly felt the loss of so many soldiers and artillery, their sacrifice had been necessary to lure the engines of Mortis in with the promise of easy kills. Four Warhounds and a Reaver was an impressive tally, but gun for gun and engine to engine, Tempestus was still grossly outmatched.

The gracefully curved sheets of burnished steel and crystal of the roof structure displayed images of the fighting around the landing fields and container port, and as much as she relished the killing of her enemies' Titans, she lamented the loss of such precious technology. No adept of Mars could fail to be moved by the destruction of so perfect a mechanism that combined the best of steel and flesh.

As deadly a threat as Mortis represented, they were not the only foes ranged against the Magma City. The cohorts of the Fabricator General had returned in full, swarming like an army of roaches on the far shores of the magma lagoon in preparation for an all-out assault. An attempt had already been made along the Typhon Causeway, a host of armoured units and hideously altered infantry storming the Vulkan Gate with gravity rams and conversion beamers.

A sally from the Knights of Taranis had broken the assault, but three of their precious Knights had been torn down to win the fight. Though they had killed well over a thousand enemy soldiers and destroyed a brigade's worth of armour, it was but a tiny dent in the vast force arrayed before them.

Other screens displayed similar scenes of war.

The equatorial refinery belt burned as running battles between engines and thousands of skitarii clashed in the blazing ruins. A ring of fire encircled Mars in imitation of the iron ring in orbit.

The hive assembly yards of Elysium, once the domain of Magos Godolph, were a silent tomb, the tens of thousands of skilled adepts having committed mass suicide in some awful ceremony to honour unknown gods.

Eridania, once the home of the most ancient and revered orders of Archivists, the Brotherhood of the All Seeing Eye, bore witness to scenes of unimaginable slaughter as the skitarii of Magos Chevain clawed their way into the kilometres-deep repository only to unleash the pestilential scrapcode. Data wheels, memory crystals and realbooks all died as the scrapcode infected every system and flooded the sunken library with corrosive gases.

'So much history and knowledge lost,' said a voice from above her, and Zeth lifted her head to look at the roof panels where her noospheric guests observed the fighting.

One panel projected the flickering image of Adept Maximal's helmet, another the handsome features of Fabricator Locum Kane.

'Some knowledge is best forgotten, Maximal,' she said.

'Don't say such things,' replied Maximal. 'Knowledge is power and no price is too high to pay to preserve it. The accumulation of knowledge should be our one and only goal, Zeth. You of all people should appreciate that. Was the Akashic reader not built for that very purpose, the accumulation of all knowledge?'

'It was,' conceded Zeth, using haptic morions to zoom in on the lumbering brutes of Legio Mortis. The carapaces and hulls of these once glorious engines were hung with black banners depicting vile, unthinkable arts of butchery. The head sections, once fashioned as stalwart warrior helms, were now leering, twisted and bestial things. 'But any knowledge that creates something like this is best deleted without hope of recovery.'

Maximal sniffed, a petulant affectation to show his disagreement.

'Enough,' said Kane. 'Save such discussions for when this crisis is over. We need to focus our attentions on how we plan to survive before we lament the loss of knowledge. Lord Dorn of the Imperial Fists sends word of an expeditionary force en route to Mars to fight our enemies. We must hold on until they reach us.'

'What else do you know?' asked Zeth. 'When will they get here? Tempestus and the Knights of Taranis have given my forge a chance to hold out for a time, but Mortis will attack again and we may not turn them back this time.'

'And my forge suffers daily attacks,' said Maximal. 'My skitarii units and war engines continue to hold, but the hordes pouring from the darkened hives of Olympus Mons are without end. I fear for what will be lost when we are overwhelmed.'

Kane nodded. 'I am aware of your tartical situation and have apprised Lord Dorn. Elements of the Imperial Army and the Saturn Regiments have been tasked with the relief of your forges.'

'And the Astartes?' demanded Zeth. 'What of them?'

Kane hesitated before answering, and even over the noospheric link, Zeth sensed his reluctance to speak. 'Captain Sigismund will make planetfall at my forge of Mondus Occulum and Captain Camba-Diaz will assault Lukas Chrom's Mondus Gamma facility.'

'Then the Astartes do not come to aid us at all,' protested Maximal. 'They seek to secure their own supplies of weapons and armour! Intolerable!'

'Agreed,' said Zeth. 'We need the Astartes if we are to defeat Kelbor-Hal's minions.'

'Captain Sigismund has assured me that once the armour and weapon production facilities are secured, his warriors will come to your aid.'

'Then let us hope they are swift in their conquests,' said Zeth.

'Indeed,' said Kane, either missing or ignoring her caustic tone. 'In the meantime, do all you can to hold on. Help is on the way and I will exload information to you both as I receive it. Good luck and may the Machine-God guide you.'

The image of Kane faded from the glass, and Zeth returned her attention to the scenes of war and death inloading from all across Mars.

Adept Maximal remained as a ghostly presence flickering from the burnished plate above her, and Zeth regarded him quizzically.

'You have something to add, Maximal?'

'Is there any word from your wayward protege?'

Beneath her mask, Koriel Zeth smiled. Even with his forge besieged and facing destruction, Ipluvien Maximal still hungered for knowledge.

Zeth shook her head. 'No. Rho-mu 31's biometrics ceased transmitting somewhere in the Noctis Labyrinthus and I can find no trace of them. I fear he may be dead.'

'So Dalia Cythera is probably dead as well?' asked Kane.

'That is probable, yes.'