Wrath of Everblight
Kallus looks almost human, although that impression is belied by his corpse-like pallor and the slightly unusual proportion to his long limbs. There is a strangely empty aspect to his features and his eyes, perhaps since that he lacked the years of practice in conveying and reading expressions that every other mortal experienced as a natural part of maturity.
After his consumption by the dragon Umbargoven, Kallus' form becomes more draconic; his body elongates and talons erupt from what remained of his hands, new limbs emerging from where there had been none.
Kallus' genesis is Thagrosh’s idea, the execution of which required testing all Everblight had learned of flesh and form as well as his mastery of his own athanc. The shard chosen for this warlock is subtly altered such that it can transform any flesh into Kallus’ body and mind. The modified shard is placed on the body of a captive, who howls as his flesh flows and melts, his bones shifting and realigning to reveal a new creature: Kallus, a blank slate informed by the vast repository of lore contained within Everblight but lacking residual memories that might distract him from his service.
Kallus' first mission is given by Vayl Hallyr, Consul of Everblight: recover the bones of a dragon so she could devise a means to track down both Everblight's siblings and the generals of Cryx. Kallus immediately knows where to go: the Castle of the Keys where Pyromalfic was defeated and consumed, even though he wasn't even born during that battle. Vayl instructs him to take a small force and enter the region unseen, past the skorne defenders to recover the bones.
Not long into his journey, Kallus finds Absylonia and her warbeasts following him. He greets her and invites her to join him, but she refuses to answer even when he speaks through their linked athanc shards. Kallus decides this might be a test of his abilities.
After entering a high-sloped valley amid the rough hills northeast of his destination, Kallus' force is ambushed by the skorne - his attempt to sneak undetected into the Castle of the Keys has clearly failed, and his army has been separated from Absylonia's. Spotting the skorne commander, Lord Arbiter Hexeris Kallus orders his men to distract the main enemy line while he breaks through and eliminates Hexeris.
Kallus cuts through the press of skorne warriors, carving a bloody path toward Hexeris, though his legionnaires are unable to break through the skorne, and most of them lie dead. As Absylonia is taking her enemy by surprise, Kallus boasts to Hexeris it's his time to fall, but Hexeris' razor worms quickly dispatch of Kallus' carnivean before Hexeris overwhelms him. Kallus takes one last look into his enemy’s face, memorising every detail before Hexeris plunges his sword into Kallus' heart.
Hexeris then orders the mortitheurge Rukaash and a Praetorian escort to bring the corpses of Kallus and a few dragonspawn to the Castle of the Keys for research. As Rukaash empties Hexeris' dissection chamber of servants and seals the doors, Kallus compels him to take his athanc shard and drive it into his own chest, in the process reforming Kallus from Rukaash's corpse. Receiving a message from Thagrosh, conveying approval, Kallus stumbles upon the ritual chambers of an Iosan dragon cult, recovers four of Pyromalfic's teeth and brings them back to Vayl. Though he returned with less of Pyromalfic’s remains than instructed, the mission is deemed a success.
Kallus later participates in the ritual to create the first archangels along with Vayl, Thagrosh and Absylonia. While Vayl and her sorcerers channel the blighted energies and activate the silver-inlaid runes of the cauldron filled with blood and Pyromalfic's teeth, the other warlocks add their own blood and the concentrated essence of Everblight into the pit, giving birth to the first archangels.
Immediately after the archangels are spawned, the Legion army is attacked by the dragon Charsaug, who has come to investigate. Though Kallus wishes to fight, Vayl compels him to help her and Absylonia protect Thagrosh, the bearer of the greatest shard of Everblight's athanc, from the other dragon, until the archangels manage to drive Charsaug away.
Everblight soon discovers the existence of a disembodied athanc, found by Cryx through some unknown means and carried south by an army led by Lich Lord Venethrax in a hastily constructed wagon designed to keep its nature contained. Hungering for another athanc, Everblight sends Absylonia, Lylyth, Saeryn, Rhyas, Bethayne and Kallus to the Wythmoor in Ord to secure it.
In 609 AR, Kallus faces off against the dragon Umbargoven, who eventually swallows him whole. However, Kallus manages to persist by integrating Umbargoven's flesh into his own with the help of Everblight. When Umbargoven clashes against Lord Toruk alongside the rest of the dragon alliance, Kallus takes advantage of the injuries Toruk inflicted on Umbargoven to claw himself out of the dragon's body.
Impressed by Kallus' ability to persist, Everblight grants Kallus a sizable force of spawn and legionnaires to the subcontinent of Alchiere to establish a new stronghold. He focuses his efforts in establishing a new stronghold in the northern reaches of the Wall of Anguish, a mountain range bordering Alchiere's eastern coast.
Kallus’ personality is yet in flux as he takes in the world and learns his place among his peers. The Nyss warlocks are all mysteries to him, with their individual motivations outside of the dragon’s wishes. His own mind is filled with the imperatives of both Thagrosh and Everblight, and he learns with a preternatural quickness.