She gave me the description as best as she could, and it's a bit sketchy, so bear with me. It was on AMC, apparently, if that's any help.
These four friends go out into the woods to meet a man they call the Professor. They keep seeing weird stuff. One goes into an invisible castle and they make talismans with twigs to ward off demons. One of the four people falls over on his talisman and breaks it. All of them but one end up getting eaten.
The survivor then winds up in the hospital where the doctors listen to his odd story. They say someone is there to visit him. He shrieks. They then cut to outside the hospital. There's this woman who smiles evilly. The screen then states "The End?" in slimy green letters.
Thanks in advance.
Equinox (1970)
IMDB: http://imdb.com/Details?0067055
One of the most asked about movies.
regards,
Apostic
It's asked about that often? Well, she'll certainly be surprised...thank you.