'Can we make it?'
'Only one way to find out,' said Pasanius, setting off for the scree slope.
Uriel buckled on his sword and ran after Pasanius, his breath ragged and strained in the toxic atmosphere. His back felt as if it was on fire, but he pushed aside the pain as he reached the slope and began climbing after Pasanius. The slope was rough, composed of dusty iron filings, craggy lumps of coal and twisted scoria. Pasanius's prodigious strength enabled him to scale the slope, albeit with great difficulty, but the loose incline gave Uriel no purchase and the harder he struggled, the further he slid back.
Screeching wails of obscene hunger echoed from behind and he risked a glance over his shoulder as the first of the delirium spectres dived from above.
'Uriel!' shouted Pasanius from a ledge above. 'Go left!'
He rolled to the left as the creature dropped from the sky, welded iron claws on its wings gouging the ground where his head had been.
He kicked out and the creature skidded down the slope, its fleshy wings beating the air in fury as it righted itself. Its shape was like that of some great, ocean-dwelling manta ray, an external skeleton formed of iron struts with its flesh a billowing sheet of patchwork human skin stitched to the metal. Screaming faces bulged across its leathery hide, a vicious ''o'' of a mouth edged in hundreds of needle-like teeth.
Another three creatures swooped from above, their jaws stretching across the entire surface of their skin and billowing wings flaring out to arrest their dives as they smashed into Uriel. The creature Uriel had knocked aside leapt into the air with a discordant howl as he struggled with the beasts that enfolded him, their teeth gnashing against his armour.
Pasanius shot the airborn delirium spectre, but his bolt passed clean through its flesh before detonating and it altered its course to swoop further up the slope to attack him with a deafening screech.
Uriel gripped the greasy flesh of the monsters attacking him and wrenched it from his armour, seeing anguished faces bulge from the surface of the skin and reach out to him. He punched through a thrashing jaw, his fist ripping through the taut skin as a flare of heat washed over him from above and he heard Pasanius shout, 'Get back!'
The beast thrashed in his grip as the others snapped and bit at him. He forced his other hand through the wound he had punched, rolling down the slope and dislodging the others. He gripped the flapping skin to either side and tore it from the iron frame, feeling the souls trapped within scream of their release.
Flickering lights and joyous cries erupted from the dying beast, and as the last soul departed, Uriel was left with an inanimate pile of torn flesh and metal in his hands. He hurled its remains aside as yet more of the creatures circled lower. Uriel drew his sword, slashing the energised blade through the flesh of the nearest delirium spectre, drawing a hysterical shriek of freedom from its jaws before it collapsed.
The last beast leapt towards him and he dived forwards, rolling and slashing high with his blade and hacking it into two halves as it passed overhead.
He heard another cry of release and saw a lifeless pile of iron struts and burning skin lying further upslope. Pasanius had his flamer out, spraying burning gouts of promethium into the air to discourage the other creatures from approaching too closely.
'Come on!' shouted Pasanius. 'I don't know how much longer this will hold them!'
Uriel sheathed his sword and stopped to grab two shorn lengths of iron from the corpse of the nearest monster before heading once more for the treacherous slope.
Driving the lengths of iron bar deep into the powdery shale like crude pitons, Uriel was able to climb the slope without too much difficulty while Pasanius kept the delirium spectres at bay with his flamer.
At last he reached the ledge and rolled onto his back as the delirium spectres closed in again. He drew his sword once more and slashed the first apart, feeling a grim satisfaction as it screamed in gratitude before its dissolution. Others burned in the fire, child-like laughter rippling from their blazing flesh as they died.
The two Space Marines edged backwards to the sanctuary of the defile, killing the shrieking, swooping beasts every time they came near. Though they killed dozens of them, Uriel could see hundreds more gathering around the mountaintops and knew that unless they found cover soon, they were as good as dead. They could not hope to hold off that many forever.
The defile was behind them and Uriel glanced along its length as it wound further and deeper into the mountain. Flocks of the delirium spectres circled lower and Uriel prayed they would not be able to follow them.
'I can't tell where it leads!' he said.
'It doesn't matter, does it?' replied Pasanius, bleeding from a patchwork of shallow cuts across the side of his head. 'We don't have much choice.'
'Give them one more blast, then follow me in!'
Pasanius nodded and shouted, 'Go!' and sent another stream of blazing liquid towards the shrieking monsters. Uriel darted into the defile, the narrow basalt walls glassy, black and reflective. It scraped against his shoulder guards, cutting grooves through the paint, and Uriel offered a whispered prayer of forgiveness to the armour's battle-spirit at such careless treatment.
Pasanius backed into the narrow defile, having to force his way sidelong through its narrow length and Uriel had a sickening vision of the pair of them trapped here and waiting to be picked off by these vile creatures.
'Damn, but it's tight,' grunted Pasanius stoically.
Frustrated screeches rang from above and Uriel saw scores of the monstrous beasts flashing overhead across the narrow strip of sky at the top of the defile. He pushed further along its twisting length, the ground sloping upwards and the distance between them and the open sky diminishing with every step.
'We're running out of room!' he called back, as a desperate scrabbling of claws and clanging of metal on stone sounded from above. Hissing beasts, fleshy wings thrashing, forced themselves down into the defile, their screeches echoing deafeningly in the enclosed space. Wails of frantic hunger and longing spat from their bodies and Uriel stabbed upwards, skewering the first of the delirium spectres on his blade.
More forced themselves into the defile, clanging and beating against one another as they struggled to reach their prey.
Unable to fire his flamer in such a confined space, Pasanius ripped them apart with his bare hands, tearing the skin from the desecrated frames with angry bellows. Uriel stabbed and cut blindly, dead flesh enfolding him and sharp teeth snapping at his face. The sound of tearing skin mingled with their grunts of pain and the incongruous noise of joyful souls escaping their hideous torment as each beast died.
'Keep going!' shouted Pasanius in a lull between the ferocious attacks.
'I don't know what's ahead,' answered Uriel.
'It can't be any worse than this!'
Uriel couldn't disagree and forged onwards, wiping clotted blood from his forehead and desperately seeking somewhere that would offer better shelter. The delirium spectres resumed their circling above the defile, patiently waiting for another chance to attack.
The defile twisted and turned, each step winding further into the mountain until at last it turned downwards and led out onto a narrow path that ran along the side of a sheer cliff.
The rockface fell away for hundreds of metres on one side of the path and at its end Uriel could see a narrow cave, its entrance surrounded with a forest of long iron spikes hammered into the rock.
'There's a cave ahead,' said Uriel. 'Looks like someone has used it to hide from these things already.'