Ulkair

Ulkair is an incredibly powerful Great Unclean One, a Greater Daemon of the Plague God Nurgle.

History
The Greater Daemon known as Ulkair has been a blight upon mankind since ancient times. Over 1,000 years before the current age in M40, the Imperial world of Aurelia, located in the Aurelian sub-sector of the Korianis Sector, was engulfed in a prodigious warp storm. The resulting turbulence pushed the planet out of its natural orbit causing the world's environment to plunge into an unnatural ice age. The world became entirely engulfed in ice as the temperatures plummeted, turning Aurelia into a frozen wasteland. Much of its population had died as a result of the sudden frigid environmental changes. Azariah Kyras was a Librarian of the Blood Ravens Space Marines Chapter serving alongside his master Moriah, the Chief Librarian of the Blood Ravens. When Ulkair manifested on the doomed planet he was confronted by Moriah, who managed to wound the Greater Daemon before dying from his own mortal wounds. Moriah's successor Kyras, proved luckier and managed to defeat Ulkair, imprisoning the immensely powerful daemon on the frozen planet. Then the Warp took the world and Azariah Kyras along with it. Ulkair remained trapped within his prison for over 1,000 years until the invasion of the Black Legion Chaos Space Marines invaded Subsector Aurelia. Led by their thrice-damned leader Chaos Lord Eliphas the Inheritor. The Black Legion was intent on releasing Ulkair the Great Unclean One from his imprisonment upon the subsector.

A thousand years passed, and the 5th Company of the Blood Ravens Chapter found themselves tasked with the dangerous mission of exploring and clearing an infested Space Hulk known as the Judgment of Carrion. The 5th Company took serious losses from the groups of Tyranids and daemons that infested a space hulk. Azariah Kyras suddenly appeared amidst his fellow Blood Ravens on the Hulk and used his psychic abilities to aid Apothecary Galan, the remaining ranking officer in the company, in defending the surviving Battle-Brothers from the Hulk's hideous inhabitants. The remains of the 5th Company, despite Kyras' aid, were still trapped on the Space Hulk, unable to get back to their Thunderhawk gunships and escape.

At the same time, Galan found himself haunted by a malignant daemonic presence that Kyras identified as Ulkair, the Greater Daemon that the Blood Ravens had suffered terrible losses imprisoning, and which had caused Kyras to be lost in the Warp for centuries. Unbeknownst to his battle-brothers, Kyras had been corrupted by Chaos during his long imprisonment in the Warp with the Greater Daemon. He sought to corrupt his fellow battle-brothers by enhancing their despair and playing on their fears. To gain the escape of the remains of the 5th Company from the Judgment of Carrion, Kyras entered into a pact with Ulkair in which in return for the Blood Ravens' escape from the Space Hulk, Galan was possessed by a daemon. When the 5th Company escaped, both Kyras and Galan were hailed as heroes of the Chapter and Kyras was welcomed back into the fold as a lost Battle-Brother.

As the Black Legion invaded Subsector Aurelia, Eliphas the Inheritor and his minions went on a quest to capture several Space Marines which would serve as a sacrifice to break Ulkair's prision. Manifesting into the body of a Plague Marine, Ulkair start to break his prision, which caused Planet Aurelia to be torn apart. The Force Commander and his squads would be then tasked to defeat the Daemon before it freed himself with the aid of Captain Gabriel Angelos and his own forces. As the Force Commander passed through the forces of Chaos and defeated Eliphas in battle, they eventually became face-to-face with the Daemon itself. After a long and hard fought battle, Ulkair was once again defeated and imprisioned, but remarked that his prision was cracked and weakened, and he would soon rise again to destroy the Blood Ravens. Despite his defeat by the hands of the Force Commander, Ulkair's presence was still active in Aurelia, where it corrupted the minds of several Imperial Guard regiments on the planet.