Abyss-class Battleship - Furious Abyss: During the latter days of the Great Crusade, the Fabricator-General of Mars, Kelbor-Hal, had already thrown in his lot with the Traitor Warmaster Horus and committed to his cause. He had been tasked with the construction of a mighty vessel of unique design, an Abyss-class Battleship, built on a scale never before seen by Humanity.Kelbor-Hal had allowed the commissioning of vast quantities of materiel, menials and munitions in the construction of the mighty battleship because it suited his purposes. Horus had unfettered Mars in its pursuit of the divine machine, countermanding the Emperor's restrictions on what technologies the Mechanicum could research and develop. For Kelbor-Hal the question of his allegiance and that of the Mechanicum was one of logic, and had required mere nanoseconds of computation.The gargantuan warship, christened by the Word Bearers as the Furious Abyss, had been forged with such heavy armour that it could withstand even a concerted assault from a  Laser Defence Battery. Its blunt bullet prow, and the way its flanks splayed out to encompass the enormous midsection, spoke of strength and precision.Three massive crenellated decks extended from it like the sharpened prongs of a stygian trident. Twin banks of laser batteries gleamed in dull gunmetal down its broadsides. Cannon mounts sat idle on angular blocks of metal filled with viewports that hinted at the myriad chambers within.The rapacious bristle of the defensive turrets along the dorsal and ventral spines, and the dark indentations of the torpedo tubes, shimmered with violent intent. Spiked antenna towers punched outward from multitudinous sub-decks, interspersed with further weapon arrays and torpedo bays. The warship's ribbed belly shimmered like oil and was replete with dozens of fighter hangars.At the stern, the huge cowlings of the exhausts flared over the deep glow of the warming engines, primed to unleash enough thrust to force the warship away from Thule. Like chrome hexagons, the engine vents were so vast and terrible that to stare into their dormant hearts was to engulf all sense and reason in a fathomless, darkened void.Finally, sheets of shielding peeled off the prow, revealing a massive figurehead: a book, wreathed in flame, wrought from gold and silver, intended to represent the Book of Lorgar. Words of Lorgar's choosing were engraved on the pages in letters many metres high.It was the greatest and largest vessel ever forged by Humanity, unique in every way and powerful beyond reckoning. This vessel had been crafted for the Word Bearers, and in the Jovian shipyards its long-awaited construction had finally reached an end. The Furious Abyss was to be a blow against the Emperor, a blow for Horus. None would know of the vessel's existence until it was too late.The Furious Abyss was manned by one thousand Astartes, a full Chapter of the XVIIth Legion split into ten companies, each a hundred Space Marines strong. The Legionaries were resplendent in their new crimson-coloured power Armour, replacing the Legion's original grey, sheaves of prayer parchment, scorched trails of vellum writ over with litanies of battle, and the bloodied pages ripped from sermons of retribution also affixed to their battle plate, openly declaring their allegiance to Chaos Undivided.They were led by Fleet-Captain Zadkiel, a devout and zealous Astartes and a deep believer in the Word of Lorgar. He was charged by the Dark Apostle Kor Phaeron to lead the assault upon the world of Macragge, where the Word Bearers would strike the first blow against the hated Imperium of Man.But ultimately, Zadkiel failed in achieving his objective when the Furious Abyss was boarded by a small ad hoc force of Loyalist Astartes who had learned of the Word Bearers' role in Horus' rebellion and who proceeded to sabotage the massive vessel's plasma reactors and destroy it before its array of formidable weaponry could be brought to bear against the worlds of Ultramar.