What is "vecna"

The fictional character Vecna has been named as one of the greatest villains in the Dungeons & Dragons roleplaying game.

Originally from the World of Greyhawk campaign setting, Vecna was described as a powerful wizard who became a lich. He was eventually destroyed, and his left hand and left eye were the only parts of his body to survive. Even after he achieved godhood—being a member of the third edition's default pantheon of D&D gods (the pantheon of Oerth)—he is still described as missing both his left eye and left hand. Vecna's holy symbol is an eye in the palm of a left hand.

Vecna's "right hand man" and then ultimately his betrayer is Kas the Bloody-Handed, a vampire whose sword, the Sword of Kas, is also an artifact.