Really need help>>>>>>>>>>>>>>>>>>>

[Swingcaptain]

Does anyone know the name of an old horror movie I saw as a kid, it was around 1978-1982......Was on Betamax video............
All i can remember was a bunch of people messing around in this old house and the window comes down and halves someone in 2 when they are trying to escape,
Big black figure at top of stairs, think also maybe a preist in house and round saw blade jumps off the floor into his chest and starts going round etc ............I have in my mind , THE EXECUTIONER or something like that but could be totally wrong LOL
Would love to find out the name of the movie.............