When it takes control of an abyssal layer, a demon lord can mold the demons there. Bonegouge assassins are believed to be the creation of Orcus. In today's Demonomicon
excerpt, a bonegouge assassin is wholly focused on its assignment. It lusts after nothing and follows the orders of its master without question.
Arcana DC 29: The discipline, loyalty, and singlemindedness of the bonegouge assassin are atypical of demonkind. Some sages believe these creatures were interlopers that first became demons through Orcus’s manipulation of abyssal energy rather than as pure creations on his part.
It is said that Orcus crafted the first bonegouge assassins from a guild of shadow assassins. The Lord of Undeath trapped guild members in pits near the crystalline heart of the Abyss for more than a century, infusing their souls with abyssal power. Once transformed, the assassins were fed an endless stream of combatants, perfecting their skills and sealing their place at the right hand of their master.
Friday: Demons often die in startling ways. From the lowly dretch to the powerful balor, the intrinsic chaos of the demonic form lends itself to dangerous death throe attacks.