The Glamor, was an evil magical item. It was used in the episode, "The Tale of Jake and the Leprechaun".
In order for a banshee to survive, every seven years it must make a human being drink this potion. Then they have thei
r victim recite a specific verse: "Turn me now into spirit bright and leave behind the human plight".
The victim has to do this multiple times, for it to fully take effect. Usually, they will trick their victim into drinking this potion. The facade might be something as innocent as just rehearsing a part of a play.
Then soon enough, after saying the oath and drinking this potion many times, the victim will be transformed into a small helpless creature. One that somewhat resembles a frog. This is known as a changeling. The banshee is in complete control of it for the next seven years. This will help them to slowly feed off the small and helpless creature's soul.