'Yes, my princeps,' replied his steersman, and Cavalerio felt the ancient machine respond, its vast and complex manoeuvring systems reacting with the speed of a brand new engine. Cavalerio felt the heat build as the monstrously powerful cannon on his left arm powered up.

He saw the stricken Warlord slow and relished the fear its princeps must be feeling to be so achingly vulnerable. With no shields and his engine burning, his fight was over.

'No, that won't do you any good,' chuckled Cavalerio as the volcano cannon fired and struck the Warlord's shields dead on, battering the last of its protection away. The first blast was immediately followed by two more, and the Warlord's upper carapace vanished in a thermonuclear blast as its reactor detonated.

'Centre Warlord's shields failing!' shouted Palus. 'It was too close to the explosion!'

'All stop,' ordered Cavalerio. 'Reverse left step and bring us back about, Lacus. Divert all shield power to volcano cannon, I want to make this shot count!'

His crew hastened to obey his commands, and Cavalerio felt the groaning strain of metal all around him as he pushed his engine to the limits of its endurance. A moment of doubt flickered across his mind as he remembered doing the same thing to Victorix Magna, but he pushed that thought aside.

canted Cavalerio.

A flurry of impacts struck his torso and carapace, and Cavalerio grunted in pain, his flesh convulsing in sympathy with his wounded engine. He felt the damage to Deus Tempestus, but shook off the pain. If his engine was paying the price for his tactics, then so too would he.

'Gun charged, my princeps,' reported Kuyper. 'Solution locked.'

Cavalerio snatched control of the weapon from his engine's gun-servitor. 'Firing!'

Once again the volcano cannon unleashed its deadly fire, the searing bolt of destruction enhanced with all the power Cavalerio could give it.

The enemy Warlord's shields absorbed the first microsecond of the impact, but collapsed with an explosive detonation that tore the upper tiers of its armour away like paper in a storm. Cavalerio kept his aim steady as the fire built in his arm to a raging, searing sensation, and the enemy Warlord vanished as his fire burned through its hull and sliced it almost in two.

The crew of Deus Tempestus cheered as the Warlord broke in two at the waist, its legs left standing as its torso and upper carapace crashed to the ground in a flaming arc of molten metal.

Cavalerio let out a shudder of release as he watched the Warlord die. It had been a terrible risk altering the shield strength to empower the volcano cannon, but it had paid off and now the odds were more even.

Then the Aquila Ignis opened fire.

Adept Zeth tried to remain standing, but the pain in her chest was too great. Her legs gave way beneath her and she slumped to her knees, blood streaming down her chest and back from where Remiare's projectiles had pierced her armour and body.

She looked down at her breastplate, seeing the void projector still intact on her chest, then looked up in surprise. Remiare smiled and spun the pistols to face her, relishing Zeth's look of confusion.

'I suppose you're wondering why your personal void didn't save you,' said the assassin as she skimmed over the ground, circling the ring of steel columns that surrounded Zeth. 'These rounds are hand-crafted in the null-shielded forges of Adept Prenzlaur, and utilise technology similar to that found in the warp missiles used by Titans.'

'Actually,' said Zeth, coughing a wad of blood into her mask, 'I was wondering how long it would take for the noospheric trip-code I've been broadcasting to affect you.'

Zeth saw Remiare's surprise in her biometrics and laughed. 'You think you are so clever, assassin, but I am a high adept of the Mechanicum! Nobody's cleverer than me.'

Remiare cocked her head to one side, analysing the connection between her and Zeth on the noosphere.

'No!' she cried, seeing the exquisitely elegant code worked into the data packets passing into her augmetics, which was even now silently and secretly shutting them down.

'Too late,' hissed Zeth as Remiare's magno-gravitic thrusters cut out and the assassin dropped to the floor of the chamber with a heavy thump. Remiare's knees buckled as she landed, unused to feeling herself on the ground with such a weight of useless dead metal on the ends of her legs.

'Right now your enhanced metabolism is trying to reboot your systems, but it won't do you any good,' said Zeth, using the extruded mechadendrites that were still hooked into the steel columns to haul herself to her feet. 'It's already too late for you.'

Zeth fought to control her breathing as her augmented nervous system assessed the damage to her body. One of Remiare's bullets had severed her spinal cord and she could feel nothing below the waist, but her metallic limbs were more than capable of supporting her for long enough to finish what she had begun. Pain-balms and stimulant drugs flooded her body to keep her conscious and she smiled as the agony of her chest wounds faded.

It was temporary, she knew, and her body was dying even as it eased her pain.

'I'll kill you!' hissed Remiare, fighting unsuccessfully to raise her pistols.

'No you won't,' said Zeth, before turning to address the primitive-looking servitor. 'Polk.'

The servitor moved to stand before the assassin, and Remiare let out a gasp of recognition as it drew back its hood.

'You remember Polk, don't you?' asked Zeth. 'You made sure my apprenta's mind was damaged beyond repair, but even a damaged mind can be rendered into something useful. Oh, he's a crude and ugly thing, I know, but his very crudity is what's protecting him from the trip-code that's affecting you.'

The servitor that had once been Kantor Polk bent down and lifted the limp form of the assassin from the ground, her struggles feeble as she tried to fight off Zeth's debilitating code streams. Polk's crude, piston-augmented muscles held Remiare immobile, and Zeth read her terror and incomprehension of the situation in the flaring spikes of her bio-electric field.

'Dispose of her,' ordered Zeth, pointing with a free hand to the shaft in the centre of the chamber that dropped through the forge to the magma beneath. 'And hold her tight all the way down.'

Zeth turned away, focusing her attentions on the steel control columns that linked her to the vast and complex structure of the Magma City's core systems. She looked up at the glowing schematic of her forge and with heavy heart issued the last of her macroinstructions.

Tharsis Hastatus, an engine that had marched to victory on a hundred worlds, was obliterated in a single salvo. A punishing volley from Aquila Ignis's hellstorm cannon stripped her of her shields in an instant, and a devastating impact from its plasma annihilator reduced it to smoking, white-hot debris.

Cavalerio felt the death of his friend and comrade, Princeps Suzak, like a knife to the heart, and fought to control his anger and grief as they threatened to swamp him. The Manifold held him in its grip and his attention was firmly dragged back to the battle.

'Situation report!' he barked. 'Who's still standing?'

Palus sent out an active pulse of auspex energy to burn through the interference caused by so much powerful weapon discharge and reactor explosions. 'I'm only getting returns from Metallus Cebrenia and Raptoria,' he said, his voice heavy with disbelief. 'Aeschman's skitarii are still fighting, but they're almost gone.'

So caught up in the furious combat was he, Cavalerio had quite forgotten that an equally bloody conflict had been raging beneath him on the ground. In an engine war of such ferocity, infantry was virtually an irrelevance, but it never paid to forget the courage of those who fought beneath the battling leviathans.