Screaming Vortex - Sacgrave: From realspace, Sacgrave appears to be a fist-shaped gnarl of black rock barely the size of a small moon. Sacgrave's Warpshadow, however, is out of all proportion to its physical presence. It stands athwart the third fluvial extension of the Screaming Vortex where its anomalous presence breaks that comparatively calm channel into the raging fifth and sixth interstices.From this position Sacgrave dominates a large part of the Screaming Vortex as many vessels are pushed close by it as they battle the raging currents of empyric energy. The dense rock of Sacgrave has been seared across every inch of its surface by raging Warp storms, leaving it black as soot and twisted into a thousand fantastically faceted pillars.No one knows who originally settled on Sacgrave and built the first fortifications there, but they are constructed on a truly monumental scale. Thickly buttressed towers of basalt and onyx rise across its angular landscape, crowned with jagged battlements of adamantium and unbreakable crystal. In many places, the towers are clustered so thickly that they interlink, forming bastions and strongholds according to no logical pattern.A maze of vaults and tunnels are driven deep into the rock beneath them, so deep their furthest reaches have never been explored. The place was clearly not made for Humans: its doorways gape wide enough for six men to walk abreast, its steps are knee high and its lofty ceilings disappear into shadows high above. Later inhabitants adapted Sacgrave to their own purposes; studding the towers with weapon pits and auspex systems, adding landing pads and docking booms, emplacing plasma furnaces and Void Shield generators in dark, silent vaults.For Terran centuries, a succession of robber tyrants and pirate kings held sway over Sacgrave and its walls are soaked with the blood of innocents. The last claimant of the fortress were the enigmatic Shadow-Margraves who sought to clone a dynasty through the dark arts of gene-manipulation and Heretek science. Some reckoned the original Shadow-Margrave of Sacgrave to be a Renegade from the Imperium. According to different tales, he was a Rogue Trader who became trapped in the vortex, or a Radical Inquisitor fleeing Puritanical opposition, or a rebellious nobleman avoiding Imperial justice. Others hold to darker tales, that the Margrave emerged from the depths of the Lower Vortex, and that he was a thing neither Daemon nor mortal.It is a certainty that the Shadow-Margrave ruled Sacgrave with a rod of iron and extorted a heavy tithe from passing voidships to pay for his obsession. Over time and after a great deal of bloodshed, the Shadow-Margrave succeeded in bringing order to the fractious pirate clans of Sacgrave and bending them to his will.Under the Shadow-Margrave's reign, the pirate fleets of Sacgrave swelled from a handful of starships to vast armadas. Bloodthirsty crews from all over the Screaming Vortex flocked to their banners for the promise of plunder and wanton slaughter they offered.  Their raids escalated until whole worlds were ravaged by red-handed reavers, their miserable inhabitants enslaved or butchered out of hand. Some whispered that the Shadow-Margrave had pretensions of taking over the Gloaming Worlds and forging an empire, or even taking their armadas beyond the Screaming Vortex to confront the Imperium itself.Perhaps that vow held the seeds of the Shadow-Margraves' destruction, their wishes being granted by some precocious Daemon lord when a fleet arrived unexpectedly in the vicinity of Sacgrave. The pirates attacked without hesitation, squadrons of shark-nosed raiders blasting into space to assault the fleet while their heavier vessels hurriedly readied themselves for battle.As the raiders closed, they were shocked to see that the vessels were not reavers. They were not even Human. Instead, the sweeping solar sails of an Aeldari battlefleet eclipsed the stars. A mighty Aeldari warhost of the Craftworld Kaelor and a dozen Aeldari Corsair fleets bore down on Sacgrave. Against them, the hard-bitten Renegades threw themselves into a fight to the death.The Aeldari blasted the first wave of pirates from the skies with mercilessly accurate gunnery even as they closed to bring their own weapons to bear. The darkness around Sacgrave lit with the dying agonies of countless vessels, falling to the terrible brightness of the Aeldari macro-lasers. The immense Dragonship Un'Alash Denasal -- "The Fury of Dawn" in the Aeldari Lexicon -- led the vanguard, its powerful Pulsar Lances burning a half-dozen raiders to cinders.Finally, the larger pirate cruisers rose to engage and the battle became less one-sided. The Slaughter-class Cruiser Benediction of Vax led the charge, its captain Indolous the Gorger directing a ferocious hail of fire against the Wraithship Fate of Eternity. Though his auspex was fooled by ghost-shapes, Indolous simply closed until he could see the vessel with his own eyes. Fiery explosions enveloped his prey, the elegant lines of the Eternity crumpling and burning under a terrible bombardment.Indolous had little time to enjoy his victory as moments later the Benediction of Vax was sliced in two by a spread of torpedoes from the Shadow-class Cruiser Forgotten Twilight. As the Benediction disintegrated in a violent burst of plasma, the Aeldari Corsairs hit the Chaos reavers from the side, pummelling their ships with salvos of torpedoes.The pirate captains that escaped the battle swore afterwards that it was lost in that moment, as first one ship then another turned away to escape the infernal cauldron of fire, their great armada unequal to the test of fighting opposing warships on even terms. The Aeldari harried them relentlessly, releasing clouds of fast-moving attack craft to chase down the fleeing Chaos ships.Sacgrave provided no protection for those that fled to it. The Aeldari swept in to pound the fortress like the fists of an angry god. Mighty towers shuddered under the impacts of torpedoes and Pulsar Lances until they cracked, toppled and melted into lakes of slag. Elegant landing craft descended to the surface, disgorging troupes of brightly-hued Harlequin warriors whose grinning masks mocked those they slew. None could stand against the warrior dancers, or their allies. It is said that amongst the warriors strode four Human knights clad in silver armour. Even the most hardened Chaos reaver crumpled against the fury of their bolt-rounds, or died from the reaping strikes of their swords and halberds.In despair, the surviving pirates scattered in all directions as best they could. The Shadow-Margraves fled aboard their powerful grand cruiser, the Kasserkratch -- its capacious holds crammed with looted treasure, if the legends are true. The Aeldari and their mysterious Human allies vanished as suddenly as they appeared, caring not for the survivors of Sacgrave. Some wonder if their goal was to see the alliance of the Shadow-Margraves split asunder, so that they would be stayed from fell deeds in the distant future.The Shadow-Margraves of Sacgrave vanished as well, though myths and rumours about them still abound in the region. The Aeldari bombardment ruined Sacgrave but it did not completely destroy it. Even the hellish fury of their warheads was not enough to topple all of the towers or penetrate the deepest vaults. Over time, scavengers and pirates have crept back in to Sacgrave to occupy the surviving towers.The scattered groups lack a single strong leader and skirmish incessantly as they pick through the chaotic landscape of tumbled basalt walls and shattered buttresses. Persistent stories of huge fortunes found buried in the rubble bring a steady influx of new hopefuls to Sacgrave, feeding a permanent community of weaponsmiths and ammunition merchants in the upper vaults.To date no vast fortunes have been unearthed on Sacgrave, although everyone knows a story about someone who really knew someone who struck it rich. Less-rewarding prizes have certainly been found -- unstable warheads, autonomous battle constructs or ravening xenos from ancient and unpleasant menageries. Every single scavenger that has entered the lowest accessible vaults has failed to return, prompting yet more tales about how the vengeful ghost of the original Shadow-Margrave is down below guarding his last and greatest treasures.Some hold, rather, that the original builders of Sacgrave never left, and that the reverberations of the destruction wrought above have awoken them from their slumber in the deepest vaults. Now they stalk through the darkness and enact unspeakable punishments on any that dare to venture into their realm.Whatever strange and deadly denizens lurk in the lower vaults, they have failed to quell the ardour of the treasure seekers and instead created a brisk trade in maps, guides, and protective charms of the Dark Gods for the entrepreneurs dwelling above.