Raven Guard - Specialist Ranks and Formations: Mor Deythan - The Mor Deythan was an elite unit of the Raven Guard Legion during the era of the Great Crusade and Horus Heresy in the late 30th and early 31st Millennia. Created by the Raven Guard Primarch Corvus Corax, the Mor Deythan were used as elite reconnaissance troops or scouts. Nicknamed "Shadow Masters", these elite Legionaries were rumored to have inherited a modicum of the unique trait of their genetic father that allowed them to "Shadow-Walk", enabling them to deny their presence to anything with a mind, making them effectively invisible. The Mor Deythan utilised Chainswords and Bolt Pistols as their primary weapons but often deployed Sniper Rifles, Shotguns or other rare weaponry such as Volkite Weapon. In battle, they utilised a specially developed battle-cant called "Stalk Argot", that consisted of a series of sighs and whispers that were nigh-distinguishable from wind and other environmental sounds. When the Emperor came to the newly renamed moon of Deliverance, those young enough to withstand the augmentations became the first Space Marines of the XIXth Legion. Amongst the ranks of the first Deliverance-born Astartes were those who displayed the same unique ability as their Primarch, enabling them to "Shadow-Walk". Through some genetic quirk of their gene-seed, a small percentage of these Astartes had inherited more of their Primarch's genome than any of their Terran-born brethren. Forming a specialised unit known as the Mor Deythan, Corax utilised his formidable knowledge of stealth and sabotage to the fullest extent, training these specially selected Legionaries to be called upon to perform highly dangerous reconnaissance and guerilla missions deep behind enemy lines. Nicknamed "Shadow Masters", this elite unit was not known even amongst the members of their own Legion. Only the Primarch himself and a select group of Legion Apothecaries were aware of the Mor Deythan at the time of the Horus Heresy. Often times Corax would call upon the Mor Deythan to test highly temperamental thermal technology to help further their goals and objectives against their enemies. By the time of the Drop Site Massacre of Istvaan V, very few Mor Deythan were left alive. Many were too spread out across the galaxy performing their missions when the deadly events of Istvaan V transpired. After carrying out countless missions on behalf of their Primarch, attrition began to take a serious toll on their numbers. Following the bloody events of Istvaan V, in which a large proportion of the Raven Guard Legion were lost, only a few dozen Mor Deythan were left alive. These few specialised warriors continued to fight on against the treachery of the Warmaster Horus and his Traitor Legions until the last of their numbers finally fell in service to the Emperor. It is not known if the Mor Deythan still exist in the late 41st Millennium.The Deliverers - Despite the favour shown to the Tactical Dreadnought Armour project by Horus himself, who acted as patron to the XIXth Legion in the absence of their Primarch, many of the warriors of the XIXth Legion were ill-disposed towards the slow and bulky Cataphractii Pattern Terminator Armour. Some did adopt their use, mainly those Chapters of the XIXth Legion who had long served in the shadow of the Luna Wolves siege and heavy assault companies, becoming adept at close range and shock assaults from both mutual support and teleport deployment. The Legionaries of the XIXth Legion came to refer to these detachments as Deliverers. In the wake of Corvus Corax' return, the Deliverers were rarely called upon by the Primarch. Most were assigned to distant Crusade fleets and those who remained at Corax' side became the avatars of his carefully controlled anger, loosed when an enemy proved itself worthy only of utter destruction.Shadow Wardens - When he was their leader during the slave uprisings on Lycaeus, Corax' peers insisted he be watched over by a bodyguard lest the slave overlords or some other rogue element attempt to assassinate him. While he resented this, Corax allowed it, as much for his followers' peace of mind as for his own safety. Having joined his Legion, the bodyguard followed, being formed into an Honour Guard known informally as the Shadow Wardens. It was said that they were ever present, though often unseen when their Primarch went to war, and that none could avoid their gaze. Indeed, only one individual was ever able to do so, and that was Corax himself, giving credence to the stories that Corax was able to slip his own shadow should he choose to do so.Shadow Killers - Amongst the Raven Guard and the XIXth Legion that preceded them, there was a tendency amongst combat veterans placed in situations of extreme stress to forsake all pretense of self-preservation, fighting with a terrifying, silent determination and the sole aim of causing as many casualties and as much destruction as possible before succumbing to their foe. This strange blood-soaked ennui that drove many amongst the Raven Guard to sacrifice themselves in battle was known among the Terran XIXth Legion as becoming "Ash Blind", while the Raven Guard native to Deliverance knew it as the "Sable Brand", a condition heralded by the darkening of the entire eye to black. Those warriors who survived their suicidal furies sometimes recovered, their brethren never mentioning the incident in a typically Raven Guard display of reticence, but more often were evermore plagued in combat by the urge to slay until death took them, paying no heed to tactical plans. The XIXth Legion, in the days before Corax' return, made little attempt to organise the Ash Blind on the battlefield, relying on the flexible nature of their tactical doctrines to make the maximum use of their suicidal urges when they took hold. The Raven Lord turned this aberrant effect of his gene-seed into a valuable weapon in his tactical arsenal, forming those afflicted by the Sable Brand into units of Shadow Killers and employing them as shock assault troops and assassins. It was the employment of such troops that allowed Corax to best his brother Roboute Guilliman in several simulated battles, an unexpected tactic that the lord of the Ultramarines was quick to adopt into the Legiones Astartes order of battle, creating the Moritat as it was later known amongst the Legiones Astartes.Dark Fury Assault Squads - The Dark Fury Assault Squads were utilised by the Raven Guard Legion to conduct focused decapitation strikes upon specific, pre-designated enemy leaders against the backdrop of the carnage of battle. Far from subtle assassins striking unseen from the shadows, the Dark Fury ascended into the very midst of the battlefield, equipped with vicious Lightning Claws fashioned after those carried by their Primarch Corax. These squads were often deployed from the holds of specialised transport vessels such as the Darkwing Pattern Storm Eagle Gunships or the open frame Whispercutters, leaping from great heights to descend upon silenced retro thrusters of their Jump Packs directly onto the heads of their unsuspecting target. Their squad leaders, known as the Choosers of the Slain for good reason, engaged the target while the warriors cut down any retainers who dared attempt to intervene. The result of a successful decapitation strike was utter confusion in the ranks of the foe, and the complete breakdown of the enemy's chain of command.