Nightwish (1989)

Using sensory deprivation techniques, a doctor of parapsychology provokes his students to examine their own deaths in evermore horrifying circumstances. Roles are exchanged and shuffled as reality and fantasy become indistinguishable and each new dreadful death proves more terrifying than the last. Their paranormal explorations lead them to an abandoned mansion in a desolate area that natives call the "Valley of Fear" where years of drinking chemically tainted water have lead to a genetically damaged population and mutant wildlife. Local legends also tell stranger stories of extraterrestrials which the students attempt to explore