An'kha'arak is a Greater Daemon of the Blood God Khorne, known as a Bloodthirster. An'kha'arak led a Chaos incursion on the Imperial world of Toreus in 579.M41 which he conquered and ruled for 300 Terran years as a Daemon World before the grip of the Warp upon this corner of reality weakened and he was drawn back into the Empyrean.
The only known record of the vile daemon lord known as An'kha'arak is during a large Chaos incursion that occurred in 579.M41 upon the damned Imperial world of Toreus. The doomed planet was engulfed and cut off by a prodigious Warp Storm for 300 standard years, and when it was finally rediscovered by the forces of the Imperium the planet had been utterly transformed into a daemonic visage straight out of the ancient human legends of Hell.
As the world fell to Chaos all around them, the soldiers of Toreus fought valiantly against rampaging hordes of daemons. When war raged on the flanks of Toreus' highest volcano, Mount Magathon, a legion of the Blood God's daemonic followers, led by the Bloodthirster An'kha'arak, butchered 50,000 Imperial servants.
The large blood sacrifice was very pleasing to Khorne and he decided to grant Toreus to An'kha'arak as his own personal demense. From the rocky ground, great skull-like caves burst forth and from their maws rivers of molten lava poured down upon the beleaguered defenders. Bloodletters heaped the skulls of the slain into towering piles as crimson smog filled the darkened skies.
From the volcano's summit, twisted spires of towering bone were wrought in the shape of dismembered corpses. The plains around Mount Magathon were engulfed by fire and blood, turning the once pristine farms and towns into gore-drenched cinders. Sitting upon a throne made of brass, An'kha'arak surveyed his new kingdom of blood as the flames roared from the volcano's peak. Eventually, the daemon's tenuous hold on reality weakened as the Warp rift began to falter after three centuries.
Eventually the rift closed and the daemons vanished from the mortal plane, leaving a world forever changed beyond human comprehension. The Inquisition moved in to investigate the lost planet when it reemerged from the Warp rift in 879.M41. In a rare moment of mercy, Inquisitor Thrax ordered an immediate Exterminatus action upon the Daemon World, obliterating any vestige of twisted life that might have survived.
- Codex: Daemons (4th Edition), pp. 20-21