Warsinger

A Warsinger is a member of the renegade Human Psyker group know as the Warsingers, that were once indigenous to the former Imperial Civilised World of Istvaan III. One of the more dangerous local sects, the Warsingers could produce sonic screams and blasts of sound waves. They were instrumental in the fall of the Isstvan system and the corruption of its people, including Planetary Governor Vardus Praal into the service of the Dark God Slaanesh.

Unknowingly the Warsingers along with the rest of the Slanneshi followers on Isstvan III were used as sacrificial pawns in Horus's scheme to amass those forces loyal to him without suspicion, and also rid his own Legion and those of his closest allies of those within their ranks whose loyalties he suspected.

Within hours the rebellion was in tatters, Vardus and most of the Warsingers were slain with all of the invasion force's objectives secured and tens of thousands of the enemy dead in the wake of the assault. The Loyalist Astartes were victorious, but soon found themselves betrayed when a cascade of terrible Life-eater Virus Bombs fell upon the doomed planet, launched by the Warmaster's orbiting fleet, unleashing the event known later as the Istvaan III Atrocity, dooming both rebel and Astarte alike to an agonising death.