Cyric

Cyric was the monomaniacal Faerunian god of deception, and the greater god of conflict and murder, as well as lies, intrigue and illusion. It was he who murdered Mystra and caused the Spellplague, throwing the cosmos into turmoil in an act that cost him much of his following.

Relationships
Cyric hated most of the other deities of Toril, but he particularly loathed Mystra, Kelemvor, and Bane. Cyric had no divine allies, but he made himself a wide variety of enemies. Occasionally, some gods might find themselves working with him, but it was with a level of reluctance that made it clear that they would rather be rid of him sooner rather than later.