After defecting from the Raven Guard and pledging alliance to Chaos, Kallorax established a pirate fleet in the Vidar Sector. His warband was small but effective, and set about carving out his own bloody legend. Eventually, his forces swelled to thousands of cultists, renegades, and other scoundrels. Every effort by the Imperium to stop him ended in disaster, and in desperation worlds paid Kallorax tributes to keep his forces from plundering their worlds.
Eventually, the Eldar Craftworld Iyanden emerged at the tip of the Vidar Sector and many within the Craftworld such as Yriel and his ally Kelmon Firesight demanded that Kallorax's reign of terror must end once for all less the taint of Chaos spread. Eventually after a fierce debate, it was agreed that Iyanden would take action against the Chaos Lord despite the fact that his warfleet had grown to even eclipse Iyanden's. However Yriel used sabotage and subterfuge to isolate and destroy segments of Kallorax's fleet, avoiding head-on battles. Yriel also took to using Imperial Merchant Fleet ships as bait to draw out Kallorax's pirates so that they could be ambushed. Yriel then expanded his operation to raid and destroy Kallorax's many outposts: asteroid bases, slave yards, and communications stations. Little by little, the Renegade's supply line withered and died.
Matters finally came to a head on the orbital shipyard above Agrion. Here at the Battle of Agrion, Kallorax finally came face-to-face with his elusive Eldar adversaries as 80 Iyanden ships battled doubled their number. Kallorax was coming close to victory, but after his Hades Class Heavy Cruiser Deathless Reaver was destroyed by Yriel's flagship Flame of Asuryan, the space battle tipped in the Eldar's favor. However once the Eldar boarded the Agrion shipyards, they found their Aspect Warriors taking heavy losses in the stations cramped corridors against Kallorax's Storm Bolter-equipped followers. Loathed to take any more losses, Yriel ordered a retreat and looses his Wraith-constructs guided by Spiritseers, who managed to use their terrifying strength and firepower to take the station.
In the aftermath of the Battle of Agrion, Kallorax faced a mutiny from his own forces by ruthlessly crushed it and hung mutilated but still-living rebel leaders body to the prow of his personal shuttle. Seeking revenge, Kallorax directed his Sorcerers to find him the location of Yriel's base, but unfortunately for him Iyanden had foresaw this turn of events and woven a psychic shield that obscured his own psykers vision. In a rage, Kallorax had his Sorcerers put to death and instead made a pact with Daemons, offering numbers of lives in hopes of using the foul creatures to destroy his hated Eldar enemies. In the end, the mass sacrifices by Kallorax paid off and the Keeper of Secrets N'Kari pledged his support. N'kari was able to detect the Eldar bases location even through their psychic sheld, and Kallorax's forces struck at them with a vengeance. Yriel managed to mobilize his own fleet and strike first. In the Battle of the Burning Moon, the greatest naval battle in that part of the Galaxy for many centuries, the two armada's clashed. During the battle Yriel confronted Kallorax directly as combat raged around them. However the battle proved to be a stalemate as Yriel's strikes were too weak to do the Renegade Warlord any damage, while Kallorax's cumbersome attacks were too slow to strike Yriel. Eventually however Kallorax's feinted with his Axe before striking Yriel with his gauntlet, sending the Eldar Prince reeling. Yriel fell to his knees, and Kallorax stood over his opponent and gloated in triumph. However Yriel managed to gather a final muster of wits and strength and duck under Kallorax's final blow, impaling the Chaos Lord with his sword. With victory in hand, Yriel's forces quickly destroyed the Riot Hunger. However in a last act of malice, Kallorax's surviving ships launched a devastating Cyclonic Torpedo attack on Iyanden (whose defenses Yriel had stripped), which killed tens of thousands of Eldar.