1st Black Crusade - The Tower of Silence: As the bloodshed of the 1st Black Crusade reached its frenzied heights, cities burned and worlds were stripped of people to feed the dark desires of the Traitor Legions. Leaving his Black Legion to continue their brutal reprisals and raids against Imperial worlds, Abaddon pursued his own plans.Using the howling souls unleashed into the Warp by so much death and destruction, he made a secret daemonic bargain. In payment for the feast of despair, pain and anguish Abaddon had created with his Black Crusade, the Dark Gods gifted him with knowledge of the secret location of the Tower of Silence on the world of Uralan.Cloaked in the shadow of the Eye of Terror, Uralan was whispered of in daemonic lore as a place where the gods themselves locked away their secrets. Following strands of fate unravelled by his cabal of Chaos Sorcerers, Abaddon had discovered a concealed path through the Warp and across the shifting sea of worlds beyond to reach Uralan without needing to breach the Cadian Gate.With a cadre of the Black Legion's elite warriors, each one a brutal veteran of a thousand battles, Abaddon set foot on Uralan and entered the Tower of Silence. Almost at once, the tower's guardians set upon them, ancient constructs of dark energy that shifted and flickered, their claws tearing at the ragged edges of his warriors' souls.After the bitter battle, Abaddon climbed down into the mirrored heart of Uralan. There, Abaddon wandered the massive haunted labyrinth for what seemed an age, fighting off the spirits of the dead that threatened to add him to their ranks.Eventually, Abaddon made his way towards the centre of the labyrinth where a shard of shifting darkness hung suspended in the air. Reaching out into the void, Abaddon felt the cold hilt of a blade meet his palm and he pulled it into reality; the Daemonsword Drach'nyen took terrible shape before his eyes.After the recovery of the malefic sword, the new Warmaster of Chaos became nigh unstoppable. Whole cities were burned in sacrifice to the ever-hungry Daemons of Chaos, and entire armies were torn apart by gibbering Warp entities.Abaddon's power swelled to inhuman proportions as the gods of Chaos rewarded him lavishly and he undertook acts of fiendish bravery which horrified those who stood against him.In what would become a festering thorn in the side of the Imperium, the Traitor Legions, often led by the Black Legion or even Abaddon himself, would repeatedly spill out of the Eye of Terror to burn and pillage entire sectors in the years following this first major incursion into realspace.In the light of dying stars and flaming cities, the Black Legion would indulge their hatred of the Imperium, indiscriminately killing the servants of the False Emperor and tearing down anything they saw as a symbol of the Corpse-God.During these so-called "Black Crusades", whole star systems would be destroyed in conflicts that would drag on for standard decades or centuries until, as suddenly as they had appeared, the Black Legion would retreat into the Eye of Terror, their holds filled with slaves and plunder.The Segmentum Obscurus suffered terribly in these endless wars against the fallen Space Marine Legions, but in truth nowhere was safe from their treacherous reach.This was something the Black Legion proved time and again as it cemented its infamous reputation among the armies of the Imperium as a pitiless foe.