Aftermath of Bedlam in the Big Top

It was shortly after the Mystery of the Ghost Clown, who had been Harry the Hypnotist. He had placed people in hypnotic trances, including Daphne, Shaggy and Scooby. Harry had come undone when Scooby and Shaggy had used mirrors to reflect his hypnosis back on the clown.

The power of hypnosis had attracted the attention of one of the Mystery Inc gang, which had made them buy a book on hypnosis as well as a golden coin at a pawn shop. What they didn't know, was this coin was actually magic. Enchanted by a magician to enhance any magic trick using the coin, say like hypnosis. Now, it would create a magical hypnotic trance. Rapid entrancement, perfect mind manipulation, lasting post-hypnotic suggestions, and so on...

So, now one of the gang has interest on hypnosis, a book instructing one how to perform it, and a magic coin which would make it work beyond the real thing. And that person was...