Cyric

Called the Prince of Lies and the Dark or Black Sun, Cyric is a greater deity of murder, lies, intrigue, deception, and illusion native to Toril.

His realm in Cocytus is called the Supreme Throne. His realm is nearly as mad as the god himself, the laws of nature and magic changing to follow Cyric's ever-changing whims and attempting to crush those who refuse to bow before him.

The Shattered Castle is Cyric's seat of power. Though it is nothing more than a crumbling ruin yanked from some other Plane, Cyric sees it as a grand palace befitting his position as future ruler of the Multiverse. Howlers roam its courtyard and the blasted lands around it, and Cyric sits in its highest tower, plotting mad schemes of domination.