Local Legend & Old Wives' Tales
The Black Diabolist was a cryptid, about which stories and sightings circulated throughout the western half of the continent since the days of the Kannalan Empire, and even some throughout the midlands of the Elven Nations.
Many of these, particularly among the more far flung marches of the Turamzzyrian Empire, were not so far from the truth. One of interest was generally told to misbehaving children. In this tale, the creature would draw in criminals and folk of ill-repute and demeanor into its control. It would coerce these victims into committing more and more heinous deeds until they were driven mad by those very same crimes and horrors. Most often, as the tale goes, these poor souls would fling themselves from the tallest heights they could find, or in a frenzy batter their heads against a wall or with a stone, until "the voice stopped."
In most versions of these tales, the Black Diabolist wears a mask made of bone. Others claim that while it appears as a slender, pale-skinned humanoid, its head is the skull of a lynx. Both variations however carry two facets that never change: the creature's eyes are always red gems, and it only speaks directly into the minds of its victims.
During the course of the War of Shadows, it was confirmed in several theaters of that world war that the Black Diabolist does indeed exist, most notably on the frontier of Wehnimer's Landing and the Earldom of Chastonia.
It was observed by many adventurers and mercenaries, including several knights of the Turamzzyrian Empire and the government of the Barony of Talador, that the Black Diabolist who joined with Elithain Cross was the same that aided and abetted the Dark Alliance during the Second War for the Sword. This has given rise to the rumor, however, that the Black Diabolist is not just one person, but many, an assessment reinforced by the flesh golems bearing bone masks loosed upon The Swale during the War of Shadows.