Blonde Possessed Girl Sees Devil in Mirror, Calls Him 'Father'

by Laurent
(Warwick, Rhode Island, USA)

I remember a movie from the 80's about a bunch of college students at some creepy old place running an experiment.

A blonde, possessed woman keeps looking in a mirror calling for 'Father' which is the Devil. He almost steps through to our side (we see his hoofed feet). Also, some other woman is trapped in Hell but it looks like she's under water.