The Witches’ Sabbath (1988)
A young psychiatrist falls under the spell of an institutionalized witch (Béatrice Dalle) who claims she killed a man on behalf of the devil.
From critic Zev Toledano:
Italian arthouse erotic movie about the seductive power of women as exemplified by a seemingly insane, temptress woman (Dalle) in an asylum who claims to be a 300 year old witch in search of a special man. The young married doctor drowns in over his head and hallucinates medieval fantasies along with her, his world transforming into scenes of wild Sabbath orgies of passion and strange unbridled games with a mass of wildcat witches, scenes of inquisition and torture, testing Maddalena for witchcraft with strange procedures, and other rituals to treat or kill the witch, all run by men afraid of her power. Well directed and full of wild, energetic performances.