Beautiful and tragic end saves OK movie

I was watching this on MGM (having a cool Hammer Halloween marathon) and it was just alright but that ending was really something, especially with the music. I thought of all the movies from the 80's that were about a kid traumatized by witnessing a death that then become serials killers as adults and this one must have inspired a lot of them, even if technically she was possessed.

"Affleck, You da bomb in Phantoms Yo"