"I am sworn to bring justice upon the Tyrant of Badab, even should it take a thousand years. Until then, my brothers and I have work enough to keep our swords from growing dull."
- — Grand Master Vorth Mordrak
Vorth Mordrak is a Grand Master of the Grey Knights Space Marine Chapter and is the sole survivor of an attack upon the Fortress World of Mortain by the Renegade Space Marines known as the Red Corsairs. Since that time, Mordrak has continued to be protected by the ghostly apparitions of his fallen comrades who died on that world.
In 920.M41, the Renegade Chapter of Chaos Space Marines known as the Company of the Shadow invaded the Imperial Fortress World of Mortain. The Renegade Astartes intended to perform a great Chaotic ritual that would submerge Mortain in the ethers of the Warp, transforming it into a Daemon World where their dark master could extend his influence. These vile plans were halted by the intercession of a Grey Knights strike force led by Grand Master Vorth Mordrak and Inquisitor Kracen. The Company of Shadow and their zombified thralls were swiftly defeated, and the surviving Chaos Space Marines rode the winds of the Warp back to their night-shrouded homeworld of Bastonbeil to lick their wounds. However, the victory had scarcely been gained by the Grey Knights when a fleet of Red Corsairs, led by the infamous Chaos Lord Huron Blackheart, arrived in orbit.
Thinking the planet to still be under the control of the Company of Shadow -- whom Blackheart considered rivals in need of eradication -- the pirate warlord ordered the fusion-bombing of Mortain. Caught unprepared for this savage attack, the Grey Knights on the world were all but exterminated, leaving Grand Master Vorth Mordrak as the sole survivor. The guilt of survival gnawed at him daily. The visions of his fallen comrades haunted his sleep, and their voices constantly filled his waking hours. Mordrak submitted himself to the Rituals of Purity, fearful that he had somehow become corrupted, but he was judged to be clean of any Chaotic taint. But these manifestations continued to plague him to the point of insanity. Mordrak was unable to find either the cause of his sufferings nor relief from them. The mystery deepened upon the world of Ralindiri. When the Grand Master was separated from his strike force by a teleporter malfunction, Mordrak was left crippled and stranded alone upon the mist-wreathed plains that swarmed with daemons. His weapon slipping from his nerveless grasp, oblivion closed in upon the doomed Grey Knight. But then a miracle occurred, as two score Terminators appeared out of the mists and encircled the unconscious Grand Master. Mordrak was found an hour later, surrounded by score upon score of slain daemons. The Grand Master's deliverance remained unexplained, as well as the identity of his mysterious saviours.
The mystery of Mordrak's enigmatic survival persisted for some months, until the Grand Master took the field on the Bloodplains of Belos III. This time there were multiple witnesses. The mysterious warriors appeared in all 5 major battles, always fighting in close proximity to the Grand Master. Mordrak caught clear sight of his allies, seeing plainly the apparitions' heraldry -- the same blazons borne by those Grey Knights slain upon the world of Mortain. Given form and voice by Mordrak's own psychic might, the souls of Mortain's fallen brothers had become bound to Mordrak at the moment of their deaths. Thus the cause of Mordrak's visions were finally explained. Though a powerful force, they were also unwelcome, for they continued to whisper of betrayal and vengeance. Mordrak concluded that only one individual was responsible for the deaths of his fellows -- the infamous Chaos Lord Huron Blackheart, whose Red Corsairs had destroyed Mortain. Gathering a force of Battle-Brothers, the Grand Master departed Titan in order to finally lay the fallen to rest.
Mordrak has set himself upon no small task, as Huron Blackheart is one of the galaxy's most powerful Chaotic warlords whose fleets and armies in the Maelstrom are said to rival those of the Traitor Legions themselves. Mordrak came close to achieving his vengeance on one occasion, but was cheated by the artifice of Huron. This formidable quest is further hindered by his oath to continue carrying out the Chapter's greater mission of responding to daemonic incursions, forcing the Grand Master to set aside his own quest for vengeance, often at the urgings of his spectral companions. In order to free the slain, vengeance must be won, but Mordrak and his ghostly bodyguard continue to hold true to the Grey Knights' sworn cause.
- Codex: Grey Knights (5th Edition), pp. 16, 40