Bewitched (1964)

Season 2: Episode 29

The Stephens and the Tates go to a seminar where speaker Osgood Rightmire proclaims that witches do not exist. Samantha proves him wrong by setting up a few tricks for him, but he unknowingly gets her back by calling out a spell that makes her disappear and reappear voluntarily. Endora finds out that Osgood's power comes from a powerful ring on his finger. Endora grabs the ring and makes Samantha visible again.