Throwing it way back to a rare movie called The Keep, which is based on a novel of the same name by F Paul Wilson.
Set during World War 2, Nazis took refuge in a mysterious fortress. They are warned not to stay, but they stay anyway. They are warned not to touch any of the silver crosses lining the walls. Greed gets the best of them, and they do it anyway. As consequence, they summon an ancient evil willing to make mincemeat of them. In the novel, it appears as a vampire. In the movie, it is a soul sucking demon.
When the demon is asked who it is, it replies "I am from you", which implies it is the essence of evil, and is feeding upon their evil, which gives it strength. But it is bound to the fortress, so it uses a lackey to help him escape. There is also an enigmatic man who is coming to put a stop to the whole mess.
Due to the movie studio not understanding the material, and not trusting the audiences receiving the movie well, they made some cuts to the movie. The result leaves the film feeling disjointed. It also makes it a slog to get through. By the time the payoff comes at the end, you would find yourself wishing it was over, if not for the commanding performance of one Ian McKellen who plays a doctor. You also see a young Gabriel Byrne who turns in a chilling performance as a Nazi commander.
If you are curious enough, this movie is available for rental on Amazon.It can't hurt to check it out.
Till next time, stay scared! -Tha Thrilla-