Frintezza
Frintezza is the son of Baium and was the last Emperor of the Elmoreden Empire. He was granted eternal life from a devil and now resides in the last of the Imperial Tombs, beyond a secret wall at the end of a long passageway that is connected to the main catacombs. Having all the time in the world, Frintezza spent a lot effort on improving his organ play, an art in which he achieved a considerable mastery.
He controls the demon, Scarlet van Halisha through songs he plays on his organ, which can stun those brave enough to enter his lair, paralyze, and cause other devastating attacks directly through Halisha.
Sources:
[1] Chronicle 5 Patch Notes
[2] Biography of Emperor Ying Huhai
Special thanks to lotek for the screenshot!