Haxan – Witchcraft Through the Ages is a a Swedish/Danish silent film from 1922. It depicted the Medieval church myth of what Witches were doing at night in their Sabbaths. It was banned in the US because of torture, nudity and sexual perversion. Hey, bring it on! Its rather tame by today’s standards but is very dark and disturbing for sure.
This clip is the darkest Witches Sabbath section with cool metal music by Electric Wizard which I found at the Wafturemoon blog.