Graz'zt

Graz'zt the Seductive, the Demon Prince of Indulgence, is one of the most powerful demons in the Abyss, ruling over not one, but three layers, known as the domain of Azzatar. From his Abyssal prison, the demon prince is able to telepathically communicate via his sword with its wielder, which Graz'zt left behind in the Umbra Hills of Exandria, and, with the help of deception and guile, gathers a following that gives him a status of a lesser idol.

Personality
Graz'zt's still longs for revenge against the Tal'Dorei Council for his defeat in the Battle of the Umbra Hills centuries earlier, and hopes to deceive some warrior into bringing about the Council's downfall.

Biography
According to Cobalt Soul records, Obann was once Graz'zt's Master of Wills, but was shamed and destroyed after a terrible failure to his lord. However, Obann was roaming Exandria as late as 836 PD, at which point he was unwittingly serving Tharizdun.

During the Calamity, Graz'zt presumably held a seat at the temple of the Betrayer's Rise with the other Demon Princes.

Scattered War
Several centuries later, during the Scattered War, King Trist Drassig found himself and his army with his back to the Cliffkeep Mountains, after losing battle after battle against the young warrior Zan Tal'Dorei and her rebels. Obsessed over the possibility of losing, Trist pledged his service to the Demon Prince of Indulgence, in exchange for the power to smite his foes. The bargain accepted, Graz'zt sent his demonic forces to the valley, which became a bastion of Graz'zt's influence.

Drassig's army and his new fiendish allies spilled into the Emerald Highlands (the hills south of the valley) like a river of nightmares. Aided by the elves of Syngorn, Zan Tal'Dorei and her rebels fought in the Battle of the Umbra Hills against all odds. When Zan slew Trist, the Abyssal pact ended, the Demon Prince of Indulgence was won over and banished back to the Abyss, and with it, ended the Drassig bloodline.

Aftermath of the war
The enormous amount of blood and demonic ichor was spilled on the battlefield, maknig the grass and flowers of the Highlands grow black and burnt, so that the formerly green area was henceforth called the Umbra Hills. Similarly, the valley to the north of the hills was scarred by the energies released in the battle: the trees in that forested valley dead and petrified and the whole area would come to be known as the Grey Valley.

In 812 PD, as a part of the hook called Shadows of the Past, shadow demons are still drawn to ancient Drassig war camps by the contract between King Trist Drassig and the Demon Prince of Indulgence. By 836 PD, the demons are gone.

Graz'tchar, the Decadent End, the blade of Graz'zt, was lost during the Battle of the Umbra Hills and provides a telepathic connection with the demon prince, calling from the Grey Valley for a new wielder.