Drop Site Massacre - Ravens' Flight: With hordes of Traitors closing in on the now-isolated Raven Lord and a storm of fire scything through the air, a single Raven Guard Thunderhawk, the Umbra Secundus, commandeered by the XIXth Legion's Master of Descent Alvarex Maun, successfully descended from the fire-streaked skies against the odds, and blasted a landing zone near the Primarch. Having boarded, Corax remained at the open assault ramp, and it is said his black eyes burned as he cursed the numberless hosts even as the gunship rose once more, the backblast of its rocket engines making a pyre for the betrayed dead that had fought to the last alongside their lord.Inevitably, the sheer weight of fire directed at the Thunderhawk shredded its armoured skin, tore one wing off and ripped its cockpit canopy wide open, slaying both pilot and co-pilot in an instant. Wrestling with the ruined controls even as the cockpit burned around him, Strike Captain Maun fought to arrest the sticken gunship's terminal descent, turning what would have been a catastrophic crash into a controlled landing. Though most of the crew were slain and the Strike Captain badly wounded, the Primarch survived thanks to Alvarex Maun's dedication and sacrifice, the two rejoining the Legion as the sun finally set on that great day of betrayal.Even as the Raven Guard slipped their howling pursuers, yet another torment was visited upon the war-shattered surface of Istvaan V. The flaming hulks of those Loyalist warships caught in the Traitors' ambush now began their inexorable and fatal descent. Soon the first large fragments of wreckage speared downwards, and smashed into the ground with a force equal to a planetary bombardment. The resulting explosion scoured a crater a hundred metres across and sent up a mushroom cloud tens of thousands of metres into the atmosphere. Moments later, searing debris rained down and a wave front of ashen smoke smothered all.It would be the first of many hundreds of impacts that would fall upon the embattled planet's surface over the coming solar days, weeks and months, wreaking indiscriminate destruction upon Loyalists and Traitor alike. With the wreckage falling from orbit overwhelming the Vox-net with impenetrable interference and the choking debris drastically curtailing visibility, the suriving Raven Guard pressed ever deeper into the cracked land beyond the Urgall Hills, a vast, broken region called the Illium Rifts.By dusk on that second day, little definite had been learned of the fate of the Iron Hands and the Salamanders, and so Corax was seen to pace the outer limits of the rifts, his gaze dark, his humours swinging violently between choler and melancholy. Several times he led his chosen warriors out into the hills in search of his lost Raven Guard sons, and any other Loyalist force who might survive yet. Several times he returned with Raven Guard Legionaries, having come upon them in the hills.Signs of other Loyalist survivors having broken free of the massacre at the Urgall Depression were found all about, many in the form of tracks terminating in the broken corpses of once-proud warriors run to ground like cornered animals. Throughout the night, still more scattered bands of Raven Guard staggered into the refuge, many wounded almost beyond the ability to fight, in body and in mind.Of all the horrors they had witnessed, of all the hurts they had withstood during the wars of the Great Crusade, here was an entirely new phenomenon. The betrayal that had split the Legiones Astartes in twain had inflicted upon them a wound no other foe had ever struck -- for the first time in the experience of any present, their vaunted spirit, wrought by the hand of the Emepror Himself, was stretched to the breaking point.Under the unheeded gaze of the vigilant Raven Guard, the Traitors' intent unfurled. Ultra-heavy transport barques descended from the still-churning skies. The heaviest were large enough to embark the mighty Traitor Titans, while hundreds more would ferry the bulk of the Traitor Legions' line units into orbit and away to the next phase of the Warmaster's betrayal. Far-ranging Raven Guard reconnaissance squads reported to the Raven Lord that the bulk of each turncoat Legion appeared to be departing, but that each appeared to be leaving behind it a core of warriors, to what ends they could not determine.The only Legion not taking its leave was the World Eaters, whose Traitor death squads ranged the hills and the wastes beyond, ever seeking to run more Loyalist survivors to ground and to add more flensed skulls to the growing ossuary-cairns. Angron, it seemed, would not depart Istvaan V until the slaughter was complete. Confronted with the stark reality of the strategic situation, the Raven Guard fell back upon their instilled battle doctrines.Corax instigated a cunningly conceived series of diversionary attacks that drew Traitor hunters away from the gorges of the Illium Rifts in which the Raven Guard had taken refuge and led them away into the mountains and deserts north and south of the Urgall Depression. Raven Guard squads ranged far and wide in the course of these actions, sometimes returning with more survivors, more often with fresh wounds and fell accounts of the sights they had seen. The Traitor death squads were hunting down survivors as if engaging in sport, and enacting unspeakable tortures upon the bodies of those they ran to ground.Many Loyalist survivors began to display signs of a psychotic break, turning upon their own brothers with unreasoning savagery. Soon enough, the phenomenon was repeated. A number of Legionaries who had once served in the Librarius approached the Raven Lord with their suspicions. Even without consciously engaging their psychic skills, each had detected a slow but inexorable build-up of psionic pressure.At first, they had taken the effect for a manifestation of so much violent choler unleashed in such a concentrated period and location during the Drop Site Massacre. Yet, as the days wore on, it had become increasingly apparent that something far darker and contrary to reason was occurring. It was the work of the World Eaters, and represented yet another sign of just how far the Traitors had fallen.All across the Urgall Depression and beyond, the World Eaters were raising ever taller pyramids of flensed skulls. At first they appeared random in form and function, though redolent of the death-fanes and ossuary-temples cast down on the most savage of human worlds during the Great Crusade. The act of gathering the skulls of the fallen, flensing them and piling them into vast pyramids all across the Urgall Depression and even further into the hills was revealed as some form of rite of victory.Somehow, this rite was proving to be the source of the madness that had afflicted the rescued Raven Guard and many others who tarried overlong in the shadow of the monuments. Some manner of psychic resonance was pulsing outwards from the vile monuments, filling those it touched with anger and bloodlust. Later on, a Raven Guard reconnaissance squad would witness their erstwhile allies performing savage victory rituals about the monuments, confirming to many that the sons of Angron remained at heart no more than bloodthirsty primitives. Others saw in the rituals something far darker still, something spawned long ago in the darkness of Old Night, the barbarism and savagery of the Age of Strife.It would be several years until the true nature of the phenomenon was revealed. Though their Primarch may have known more, the Raven Guard were blissfully ignorant of such things at that time, though even then it was obvious that some agency beyond the natural order of reality was abroad. Keeping his own counsel on the matter, the Raven Guard Primarch ordered a series of attacks against a small, select number of these vile structures, strike forces of chosen warriors planting Melta Bombs at their bases. The resulting detonations brought the targets crashing down in cleansing flames, and the fell psychic effect they exerted on the surrounding regions lessened, though it never entirely relented.