Eberron: Unsung Heroes
Little is known about this man, apart from his strange powers and command over aberrations. He seems to have some kind of aberrant Dragonmark that covers his entire body, and can use it frequently. He attacked Jaeryn’s ball with a host of desperate men and monsters from Khyber, killing numerous nobles and cutting off Jaeryn’s arm.
Apparently, he recruited from the Fallen district before he attacked the ballroom.