The Demon Prince of Madness Adimarchus craved to create a plane all his own. In doing so he crafted Occipitus and tore it away from the heavens and plunged it into the Abyss. But he craved more. He wanted to bring Occiptus into the Prime Material Plane. With this he forged the Crown of Woes. Adimarchus was once an angel of great power that served the lords of good but fell from his position and plunged into madness in the process. His ambition knew no bounds and the lords of good both fearing and pitying him, imprisoned him in a part of the heavens. Adimarchus’ imprisonement was vast, as the years went by, his hatred and insanity swelled until he transformed into two beings; one angelic, and one demonic. Adimarchus proved more cunning then they ever anticipated and using his power he took control of his very prison calling it Occipitus . Adimarchus’ genius did not stop there, he next crafted out sections of the planes to forge The Crown of Woes.
Adimarchus was a demon lord known as the “Demon Prince of Madness,” not because he claimed sovereignty over insanity, but primarily for his current state of mind.
Adimarchus had two forms. The first may be what he looked like when he was a celestial, that of a pale purple-skinned hairless humanoid with razor sharp metallic wings. Golden tattoo-like patterns shift across his chest. His other form was that of a lithe humanoid with ash-black skin and four tentacles protruding from his back that end in lamprey-like maws. Adimarchus can switch between these two forms at will. To destroy Adimarchus was like fighting two separate creatures; killing just one form but not the other does not slay him. Damage sustained in one form was not carried over to the other.
Adimarchus made his home on Occipitus.
Adimarchus was a fallen celestial. It was not known how or why he fell from grace, but what was rumored was that he eventually led an army of demons to invade the upper plane of Celestia. It is said the angels of Celestia repelled the invasion by casting part of Celestia (along with Adimarchus and the invading demonic horde) into the Abyss, specifically, making it the 507th layer of the Abyss known as Occipitus. Others say Adimarchus himself severed the plane and created Occipitus and that it was not actually a part of the Abyss but became a demiplane between the two planes, having aspects of both.
Despite his defeat, Adimarchus incorporated the wreckage of Celestia into the layer, and in doing so he became the ruler of Occipitus, becoming a demon lord in the process. Adimarchus went on to build an empire in the Abyss, eventually trying to bring Occipitus into the Prime Material Plane.
It turned out that an aasimar paladin named Athux went to Occipitus on a quest to redeem Adimarchus’s soul. Athux fought his way through the layer and into the throne room of the fallen celestial/ demon prince. The two fought practically to a standstill until Adimarchus gained the upper hand and sundered Athux’s weapon. Adimarchus would have killed Athux but in a rare moment of compassion sparked by his celestial nature could not bear to do it. Instead, Adimarchus kept Athux prisoner and attempted to seduce him to the side of Evil.
After Adimarchus’ defeat at the hand of the heroes Athux’s whereabouts were unknown. The heroes that defeated Adimarchus do not mention Athux.