He shrugged mentally. At least he’d tried. Glancing at the clock again with growing impatience, Severus took a breath and resumed the sonorous chant that would, as night fell across the pit’s entrance far, far above, release his new lord and master.

The land speeder hacked and coughed its way through the industrial quarter of Lettica, its dented prow trailing a long beard of black-purple smoke, dipping every few moments to grate noisily against the street before lurching upright again.

For Captain Ardias, accustomed to the clipped Codex-standard precision of Ultramarine behaviour, it was hardly a dignified mode of transport. Passing through hotly contested zones of violence — human and tau bodies mingling with those of Chaos warriors, gunfire and grenade blossoms marking every street corner — he grimly attributed the lack of pernicious fire aimed at him to the astonished amusement with which enemies and allies alike regarded him as he passed.

Like them, he considered the continued functioning of the land speeder something of a minor miracle, and hissed thankful prayers to Guilliman, the Emperor and whatever unknown techmarine had originally built the chassis. Despite the dents, sparks, smoke-belching fissures and various red-blinking warning icons, received at the ungentle end of the enormous bomb blast, the hovering contrivance delivered him safely to the shadow of the district’s central hangar with no more damage than a thumping headache and a wounded sense of pride. He was in no mood for tolerating xeno-contact when he arrived.

The blood-caked tau with the dented helmet, unexploded bolter shell still lurking within, watched him approach along the street with arms crossed, a healthy distance between his slouched position and the vast hangar.

The rogue element, Delpheus had said, before he died. The warrior with the bomb in his head.

This tau, this “Kais’, had singlehandedly wiped out the bridge of an Emperor-class battlecruiser. He’d crippled the Enduring Blade’s weapons systems, fought through the anarchy that consumed the ship to the drop pods and survived ever since. More than enough proof of his abilities. Still, it went against everything Ardias believed to consort, trust and rely upon the skills of an alien, even one endorsed by an Adeptus Astartes librarian, and drawing level with the cross-armed figure now confirmed every one of his fears.

“Fool!” he roared, leaping to the sand and drawing his pistol. “I told you to sabotage the war machine, not await my arrival! We can’t hope to stop it in time; you’ve doomed un—”

“Human,” the alien said calmly, holding up something small and silver. “Watch.”

It pressed a button.

Behind it the hangar went up like a box stuffed with firecrackers and for the briefest of moments Ardias could see the colossal shape of the titan shadowed against the flames, crisp hangar walls falling away like a layer of skin. It was a hunchback of smoke and shadow, an ogre of gargantuan proportions that basked— no, drowned — in its wreath of fire. All too soon it was lost to a series of detonations that plucked chunks from its torso and split apart its joints. Ugly gouts of plasma and promethium fuel vented outwards: fiery spouts from a dying whale, flexing and breaching its death throes in a blazing spectacle of incandescence.

An upper limb sheared away from the torso with slow gravity, tumbling downwards in an avalanche of debris. The noise of its impact jerked Ardias from his astonishment, leaving him uncomfortably aware of his proximity to the collapsing machine and, more annoyingly of the tau warrior, who stood regarding his expression of awe with tilt-headed fascination.

As he’d approached through the city he’d wondered vaguely what progress the alien might have made. He’d envisioned finding the creature’s body at the titan’s base, hurled dismissively from whichever inner tier at which its progress had faltered. He’d envisioned it cowering in a shadowy corner of the hangar, too horrified by the glory of Imperial engineering to even move. He’d imagined it failing and dying, or else succeeding with painstaking slowness. He had, to be blunt, not been confident.

He’d never considered arriving to find the job already done.

“You had better come with me,” he growled, motioning towards the land speeder, “before the whole thing comes down on top of us.”

“I’ll take that as a ‘well done’,” the alien grunted, clambering gingerly into the passenger seat.

“Do what you want. We have work to do.”

The vehicle moved off, sand mixing with soot and ash in a billowed cloudform wake. Behind it the titan wobbled uncertainly, knee joint buckling with enormous inevitability, the scene lent an eerie slowness by the scale of destruction. The building-machine toppled like a foundationless tower, tumbling apart in a riot of metal and stonedust, sparks and smoke swept along in its arc.

The noise of its impact shuddered throughout the city for long, ugly seconds, colossal slabs of armour and masonry flattening the surrounding buildings and choking everything in a tsunami of opaque dust that guzzled the light ravenously. Ardias and Kais were gone before the echoes stopped.

Kor’vesa 66.G#77 (Orbsat Surveillance) arranged itself carefully in relation to the other drones filling its airspace and, at the Or’es Tash’var’s command, trained every one of its sensors on the planetary surface.

Extending in a wide grid of sense clusters, radar-scanners and high-altitude surveyors, every available drone at the tau flotilla’s command had been hastily deployed. Weapons droids mingled with engineering apparatus, blocky chaff drones interspersed sparsely with maintenance constructs, top-of-the-range spy-sat cameras and barely sentient control-applicators seeming awkward and disparate in close proximity comparison. And every last one — from the most technologically advanced to the simplest of unipurpose models, from those with sensory equipment able to pinpoint a single individual in twenty different spectrums through a hundred tor’kans of atmosphere and cloud cover, to the lowliest of sightless fuel-gauge drones with barely enough scan sensitivity to penetrate the exosphere — trained the colossal might of their combined awareness upon the planetary surface and, in a closely choreographed orbital dance, spiralled their attention outwards from the city.

Every third mor’tek-raik’an 66.G flickered its attention across the precise bio readings and spectral signatures of Aun’el T’au Ko’vash, harvested from its memory banks and shared with the rest of the drone army. Thus did its sensor sweeps occur in three distinct segments: a reminder of its target; a momentary burst of information culled from its sensors and an alignment of the two, comparing and contrasting. The process was repeated over and over, thirty times in every raik’an, and only when the sensor reading and the memorised data matched could 66.G, or any of its comrades, be certain of having located the ethereal.

A blip moved across its target area: a series of energy emissions and gue’la-signature fuel traces moving quickly eastwards. The drone narrow focused on the reading and performed a detailed analysis. From the available data and scant vehicular information stored within its record matrices, 66.G postulated that it had discovered a “land speeder”, a low-tech human skimmer vehicle, and transmitted its discovery to the parent node on the Or’es Tash’var. A minor sensory fluctuation in the reading caused it some perplexity; an apparent Line Warrior energy signature that oscillated between invisibility and a warning-red state of crisis. Orbsat 66.G checked off the identifier-code against Shas’ar’tol records and found it earmarked for immediate broadcast. Accordingly, the drone forwarded its bizarre findings to O’Udas’s staff and awaited a response.