The Doom Marine

In the many storied annals of the Imperium, there are few figures as strange, or as mysterious, as the one they called the Doom Marine. Appearing on forlorn battlefields, long abandoned by hope, and appearing to confront the creatures of the Empyrean and their minions, this lone Astartes carves a blood red path through anything foolish enough to stand in his way. Such is his fearsome skill against creatures of the Warp, that observers have even seen daemons of the Warp recoil in his presence, even downright flee. Of the Doomed Marine himself, little is known, with his armour scrubbed of markings aside from a faded aquila, and a lightning bolt symbol on his greave. Clad in ancient armour, and wielding a chainsword, his tireless campaign against Chaos never ends. They denizens of the Empyrean fear him so much, he even has his own names amongst their kind, like the Warp Walker, or the Unending Predator. 
==History==
===Ancient History===
Due to the strangeness of the Warp, those trapped by it's tides and eddies find themselves displaced, even within time. Perhaps this accounts for the earliest sightings of the mysterious Warp Walker predating the Imperium. A ruined tableau recovered from the ruins of the city of Parnees shows a figure similar in appearance to the Doom Marine, standing over his foes. This came into the possession of the Emperor several millennia later and remained amongst his treasures in the Imperial Palace, even after his internment in the Golden Throne. He is mentioned in at least three texts produced either by daemons, or those that communed with daemons, each written before the Emperor unified Terra. Such strange appearances seemingly defy all understanding of time. In these texts, he is mentioned as appearing both in realspace, and in the Warp, butchering and slaughtering daemons wherever he found them. His name was hated, and loathed, even feared, as he carved a bloody path through them, wherever he went.
===Horus Heresy===
During the Horus Heresy, there are two confirmed sightings of the Doom Marine, though given the madness of that war, there may have been others, that went unreported, or were simply forgotten in the pandemonium. 
The first, and more detailed of his appearances, was during the Battle of Signus Prime. Truly a terrible and dark chapter for the Blood Angels, as the Legion suffered under the wrath of daemons. During the battle, a Chapter sized force was pressured into a withdrawal from a gorge where they'd been trapped by daemonic forces. While the bulk of their forces lead a break out, a demi company covered the rear, in what was expected to be a last stand. Sergeant Gediel lead the defence, and even with the successful break out, and the order to withdraw, he could not pull back without being routed and torn apart. It is then the Doom Marine appeared. Charging into battle with his chainsword, his first action was to render a Juggernaut, and it's rider with one swing. Diving into the encroaching horde, he tore apart the daemons apart, at times even using his bare hands to crush bone and tear flesh. Astounded by the violence, they used this lull to withdraw. This was one of the few pict captures of the Doom Marine, showing his Godwyn-pattern Bolter, the STC for which would not be found until long after the Horus Heresy. Their last sight as they withdrew was the Doom Marine amidst the Chaos forces, a single green figure in the midst of a tide of crimson daemons, yet his furore only grew. Despite investigations, none knew this Marine, and he was not found in the aftermath. 
The Second was during the Siege of Terra itself. With daemons unleashed upon Holy Terra, for the pleasure and perversions of the Dark Gods, and every soldier and Astartes dedicated to the defence of the Emperor, the citizenry were slaughtered wholesale. In one such Hive, the greater daemon known as Ixecoatl and its pawns, intended to sate their hunger on undefended women and children. Only the intervention of the Unending Predator stopped the slaughter. According to surviving witnesses, the lone Marine dispatched the lesser daemons, and leapt into battle against the daemon, a sick combination of flesh and machine. During the battle, he tore it's head free of it's body, and cast it aside, leaving for further prey. 
==Description and Abilities==
==Wargear==
*Imperator Armour: The Doomed wears a suit of Mark III 'Iron' Power armour, but much of it's appearance is highly unusual. The armour is undoubtedly ancient, from the dawn of the Great Crusade, but features a number of strange new feature, not present in such suits. The armour features a smaller, sleeker powerpack, similar to later generations. It also has a weapon built into the gauntlet, observers report it is some kind of close range cannon, capable of obliterating daemonkind, or even targets as heavily armour as a terminator. The armour is astoundingly sturdy, even for Iron Armour, and resists blows that would crumple other forms of Astartes Power Armour. Magos <REDACTED> was able to identify it, like one may identify a finger print, as a product of the Forge World <REDACTED>. To insure secrecy, the Ordo Malleus purge the Magos and his 600 strong retinue. 
*The Chainsword: At first glance, nothing seems remarkable about this rather simple looking, albeit outdated Chainsword. Void of markings, the weapon revs with a ferocity that sounds closer to a roaring beast, than a weapon. But seeing this thing bite into the forces of Chaos, it becomes obvious this is no normal instrument. Shredding its way through the thickest armour, and the hide-flesh of Daemons, its terrifyingly potent, even more so against the Neverborn. The weapon is illustrated in the Codex of Hexanine but the heretic Gormire, and in the Khadalian Annals, written by daemonic prophets, both professing the potency against Daemons. 
*Bolter: An otherwise unremarkable MK-Vb Godwyn pattern Bolter is often seen in his hands, though not always used in his blood lust. The weapon is strange in of itself, as ancient pict-captures from the Horus Heresy show the very same weapon in his hands.