demoniacal
From Longman Dictionary of Contemporary Englishdemoniacalˌde‧mo‧ni‧a‧cal /ˌdiːməˈnaɪəkəl◂/ (also demoniac /dɪˈməʊniæk $ -ˈmoʊ-/) adjective formal CONTROLwild, uncontrolled, and evil the demoniacal glint in his dark eyes —demoniacally /-kli/ adverbExamples from the Corpusdemoniacal• Fear gripped her at the demoniacal glint in his dark eyes.