Wiktionary
under a spell
a. (context idiomatic English) bewitched, held by the power of a magical spell.
Usage examples of "under a spell".
They acted as if under a spell or with such concentration that it had become etched in their faces and movements.
It seemed that the Adept Stile had been under a spell that the music was abating.
Maybe he had been placed under a spell of abstinence, to keep him honest.
It was amazing how alien ordinary human speech sounded when pronounced backward' Then, on paper: I'M UNDER A SPELL.