Gathered around the hulking form of the carrier Kharloss Vincennes were the Cobras of Cypria squadron, together with the one surviving vessel of Hydra squadron. The two strike cruisers of the Space Marines anchored in the shadow of the Argus. Lord Inquisitor Kryptman and the Space Marines had already deployed to the surface of Tarsis Ultra, their presence there deemed more vital than aboard their vessels. As a result, the Mortis Probati and the Vae Victus would stand off from the main engagement and utilise their fearsome bombardment cannons, rather than entering into the thick of the battle. With only a limited number of thralls and servitors to defend them, there would be no possibility of them repelling boarders and such ancient craft were too valuable to be lost in such a manner.

The tyranid fleet first appeared as a sprinkling of light against the velvet backdrop of stars, its scale magnificent and terrible. Reflected starlight gleamed from city-sized chitinous armour plates and glittered on trailing tentacles that drooled thick, glutinous slime. Swarms of smaller creatures, their fronts crackling with twisting arcs of electrical discharge, surrounded the hive ships, surging ahead of the main fleet with a speed hitherto unseen among the organisms that made up the alien fleet.

Under the power of dozens of straining servitor-crewed tugs, the hydrogen-plasma refinery drifted forward to meet the tyranids. Its hull was packed with yet more explosives and volatile plasma cells, and the magnitude of the resultant explosion was sure to dwarf the detonation of the previous refineries.

Admiral de Corte watched the tyranid creatures close on the refinery with a feral smile on his lips. Though tens of thousands of kilometres away, the refinery still dwarfed everything around it, and de Corte knew that the blast was certain to kill hundreds, if not thousands, of alien organisms. If they were lucky, perhaps another hive ship would be drawn to attack the refinery and yet another of the masters of this fleet could be destroyed.

Swarms of aliens surrounded the refinery, many passing close, but none yet attacking. De Corte resisted the temptation to order the Argus's nova cannon to fire until one of the larger beasts moved in to attack. His practiced eye watched the vanguard of the alien creatures smoothly part as they swept past the refinery, their movements as precise as the finest naval squadron's display manoeuvres.

'They're not attacking it,' said Jex Viert.

De Corte chewed his bottom lip, pondering whether to order the nova cannon to fire. So long as the refinery drifted before his fleet, he was reluctant to order a general advance and the damned aliens weren't taking the bait.

Something was wrong. The tyranids had reportedly swarmed all over the refinery the Ultramarines had sent towards them beyond Chordelis, so why weren't they doing the same now?

Four enormous creatures approached the massive construction, rippling orifices on their elongated prows filled with rotating blade-like fangs. They surged past the refinery, their long, trailing tentacles snagging on its superstructure. Whether their actions were accidental or deliberate, de Corte was unsure, but he did not like the synchronicity with which they had moved into position. Hordes of creatures with spined crests rippling upwards from their bodies like bizarre, reflective organic sails, emerged from the swarm, moving with a grotesque, peristaltic motion to take up position before the refinery.

'What in the name of the warp are they doing?' wondered de Corte aloud as another group of alien creatures, with crackling arcs of electricity spitting before them moved to surround the tentacled leviathans.

'Sir,' prompted Jex Viert, 'The kraken in the vanguard of the alien fleet are approaching engagement range.'

De Corte snapped his gaze to the plotting table and the automaton-like logisticians moving the markers representing the tyranid fleet forward towards his battle line. The refinery would have to wait. 'Mister Viert, order the monitors forward and issue clearance to engage to all ships. My compliments to each captain, and wish them all good hunting.'

'Aye, sir,' nodded his flag lieutenant.

Lord Admiral Tiberius watched the same scenes from the bridge of the Vae Victus, his own confusion matching that of de Corte.

'This is damned peculiar,' he said, rubbing a hand across his jaw. 'Why doesn't de Corte shoot?'

'I believe he is waiting for one of the hive ships to attack the refinery,' said Philotas.

'Then he has underestimated the ability of these creatures to adapt to new battlefield situations.' Tiberius did not know how right he was.

The tentacled leviathans whose trailing appendages had caught on the refinery strained against its massive weight, their bodies little more than a colossal series of powerful, interlinked muscles. Though internal fibres ruptured within them, and each creature burned so much energy in halting the refinery's forward motion that they would soon be consumed in the process, they continued hauling on its gargantuan bulk.

The vast overmind cared nothing for the individual creatures that made up the majority of its mass and directed its monstrous will at the muscle beasts. Even in death, the muscle beasts would not be wasted, their organic mass would be reabsorbed by the hive fleet and used to produce fresh warrior creatures.

The hive ships lurked in the centre of the swarm, keeping a safe distance from the dangerous intruder in the midst of the fleet.

Slowly at first, but with greater speed as they overcame the refinery's inertia, the dying muscle beasts began dragging it behind them.

Fluids and muscle fibre was shed from their bodies as the single-minded purpose of the hive mind continued to destroy them.

And the refinery followed behind them, gaining more and more speed as it returned to the Imperial battle line.

Admiral Tiberius suddenly realised what was happening and shouted, 'Philotas, open a channel to Admiral de Corte. Now!'

'Admiral?'

'Hurry, Philotas!' shouted Tiberius, descending from his command pulpit and running to the communications station as Philotas held out the brass headset and hand-vox.

The vox officer nodded as the clipped tones of Admiral de Corte and hissing static crackled from the gold-rimmed speaker on the panel.

'Admiral Tiberius, make this quick, I have pressing concerns just now.'

'Destroy the refinery. Now. The tyranids are pulling it back towards our battle line.'

'What? Are you sure?'

'I'm sure, admiral. Check your auguries if you must, but do it quickly.'

'You must be mistaken, Tiberius. How could the tyranids possibly even have the capacity to understand our intentions?'

'They learn, admiral. I should have known that we could not pull the same trick twice with these beasts. Please, admiral, we don't have time for debate. Destroy it now!'

'I shall have my surveyor officers confirm what you say, but I am unwilling to destroy so potent a weapon on a whim. De Corte out.'

Tiberius handed the headset back to the Space Marine at the vox station and marched back to the plotting table. Quickly he scanned the positioning of the Imperial fleet and felt his skin crawl as he realised the scale of the disaster that could soon befall the Imperial fleet unless they took swift action. Philotas joined the admiral, furiously entering figures into his navigational slate.

'If we move now, we can intercept the refinery, lord admiral,' he said.

'Do it. All ahead full, divert all available power to the auto loaders for the prow cannon. I want to be able to hit that refinery with everything we've got. And contact Captain Gaiseric on the Mortis Probati and get him to join us, we'll need his ship too.'