Manshoon is a powerful wizard with a metal arm. He battled the group in Gralhund Villa. Paultin counterspelled his power word: kill attempt and Strix polymorphed him into a chicken. A while later, Manshoon accosted Paultin in the Yawning Portal right after he put on the ring of winter.  Manshoon was killed by Gwyneth in the battle at the Yawning Portal. Strix took his staff of power and his robe of the archmage. Miranda took his metal hand, which continued to move after he was dead.
Waterdeep: Dragon Heist
Manshoon is a wizard who runs the Zhentarim.