Chapter 1: "The Mysterious Figure"
Before the events of Lord Kaldor Draigo's disappearance, as seen in Codex Grey Knights. Kaldor had developed a new form of Grey Knight without the consent of his fellow brotherhood members. This new unit was known as the Black Knights. They were created by Lord Kaldor for personal purposes, you see, many years back, Lord Kaldor Draigo lost ten battle brothers very dear to him at the hands of a demon prince named M'kar the Reborn. These battle brothers were his ten closest battle brothers before Lord Kaldor was Supreme Grand Master of the Grey Knights. They fought battle after battle after battle with Kaldor, they were closer than any other and wouldn't let death separate their alliance.
One day, when Kaldor and group of eight Purifiers were entrusted with the transportation demonic artifact known as the Armarkinath, of which is said to revive the dead into dark and shadowed versions of their old selves. As Kaldor and the Purifiers transferred the artifact into the Librarium Daemonica, Kaldor could hear voices coming from the weapon, promising him many things, sweet nothings that Kaldor is more than apt to deal with. The weapon was safely delivered and stored in the Librarium Daemonica, without any trouble once so ever. However, those promises of returning his loved ones still remained in Kaldor's mind, of course he wouldn't let it affect him but still, he missed them…
The next day, Kaldor returned to the Librarium Daemonica to take stock of the artifacts, as commanded by Brother Captain Stern. He told him to do this to make sure none of the weapons were lost or were beginning to disappear from the mortal realm. At first, nothing seemed out of place, until he caught a shadowy man in the corner of the room, wielding Armarkinath in one hand and ball of warp energy in the other. The details of the man were blurred due to the shadowy illusion that surrounded his person. Kaldor was shocked that he could sense his psychic signature, he felt no presence in this place once so ever, aside from his own.
Kaldor screamed out, "Heretic, stop!" Kaldor fired his storm bolter into the figure, the bolter shells went straight through him like a cloud of smoke. The figure was no more, it disappeared into a cloud of black smoke, dropping the artifact upon the ground causing it send out some sort of pulse. The pulse worried Kaldor, but not nearly as much as a mysterious figure being capable of entering their sanctum. Kaldor reported directly to the Prognosticars of the Grey Knights, asking for help in discovering what had happened. Once he had told the Prognosticars of this break in, news spread about this spectre throughout all ranks of Grey Knights, fear had struck their hearts.
After some detailed analysis, the Prognosticars came to the conclusion that it must be a demon of immense powers in illusion, most likely a Tzeentch demon of some rare variety. As for the pulse, the energy it generated seems to have filled the entire Librarium with unstable and unpredictable warp energy. However, it doesn't seem to be affecting any other artefacts in the Librarium, so the Prognosticars decided to tell a squad of Purifiers to move it to a secret vault where they could keep it away from any other demonic infiltration. And just in the case the weapon began interacting with other artefacts. Kaldor, went back to his chambers that night and spent many hours reading the Libre Daemonica, in search of that unholy demons name. He was unable to find any mention of a demon of this kind…