Share yours, I'll start if off, I have a few I heard from the platform or from other JW's.
One from the platform, a witch was studying with JW's, and she had a relationship with demons/spirits. When she was studying they turned on her and threatened her if she didn't stop. The grand finale was they materialized somewhat and surrounded her house at night.
I heard a fellow JW say when he was in school, this martial artist who was studying said let me show you how sick martial arts are. He waved his hand over food on the cafeteria counter and flames appeared on them.
One female JW said when she had to have emergency surgery and the only hospital that could do it was a catholic hospital. At some point headless nuns float into her room and try to choke her, then she yells Jehovah and they vanish.