Otwic Anthomodous
Spoiler warning: Articles include story details through Episode 47 of the main campaign and all three episodes of Parental Advisory.
Otwic Anthomodous is the former monastery elder and High Scholar associated with the ruined Aelmor monastery. His surname is one name, not an additional person called Thommadus. Anthomodous is the spelling confirmed by Jeff.
Old records and Helest's account connect Otwic's research with the Hand of Narkul. Helest says putting on the hand transformed him harmfully. The missing-right-handed apparition in the bell tower and crypts is associated with him.
Disturbing the principal tomb provokes the ghost to possess Todd. The party knocks Todd unconscious to drive it out, then defeats the apparition; Malcius's Dissonant Whispers dissipates it. During the encounter Thormir is magically aged thirty years. The presumed remains in the tomb lack the right hand.
Rory later distinguishes Otwic's possessing acolyte from the entity connected with Guthber. The accounts do not justify merging every possessing presence into one identity.