Catelexis Heresy

The Catelexis Heresy was a conflict that resulted from the Xenos cyborg known as the Cacodominus who used their formidable psychic presence to control the populace of 1,300 planetary systems. The zealous Black Templars Space Marine Chapter called a Crusade against the vile aliens and ended the Catelexis Heresy when they executed the Cacodominus. Alas, this outcome had unexpected consequences that would soon prove dire for the Imperium of Man, resulting in the infamous event known as 'The Howling.' The Cacodominus' death scream echoed and amplified though the Warp, burning out the minds of billions of Astropaths and distorting the signal of the Astronomican. Millions upon millions of ships are lost in the resulting upheaval and entire sub-sectors slide into barbarism without the dictats of the Adeptus Terra to guide them.