"Well, you can't really blame the machine, Jon," Karyn said, after the dream machine had turned to dust. "Her nightmare was written out on the screen as plain as day. Maybe you should use some restraint. I mean, if you decided to activate your mom's nightmare when knowing full well what it was, then maybe you shouldn't even be allowed to use something as powerful the stone."
She grabbed it from him and before he could protest, she said "I wish it was impossible for Jon to use the stone from now on."
The stone glowed, granting her wish.