There is no power in a Ouija board, but using a Ouija board is dangerous because it invites any spirit that happens to be hanging around to come and take partial possession of your subconscious mind. Passiveness, eagerness to receive, and indiscriminate acceptance are especially dangerous, because they are an open invitation to every spirit that has an agenda. You may take my word for this or not, as you please, but I proved it for myself by experience.
But, see, if there was a spirit hanging around, it would already be supernatural. Why would it need your invitation?
I mean, if all it takes for a spirit to get into your mind is a piece of cardboard from a game manufacturing company, we’re all pretty much screwed. Just think what could happen next time you use a hammer.