It's hard to imagine a film this gruesome being shown on commercial TV stations, but it was a staple on the defunct "Creature Features" TV show on KTVU Channel 2 in the 1970s.
Produced by the same people behind the excellent "Brotherhood of Satan," the film opens with a young women being murdered by a busy-eyed warlock, who strings her up, slashes her throat and drains her blood into an urn.
As new killings terrorize the swamp area where the first woman was murdered, a psychic researcher, some helpers and a magazine reporter show up to investigate. Naturally, they run into some witches. In a hilarious scene that no youngster watching this film on the tube ever forgot, one of the researchers targeted by the warlock is forced to run topless for her life. Because producers wanted to avoid an X-rating, she's shown running cupping both her breasts with her hands! Despite some laughable moments, "Witchmaker" delivers a lot of atmosphere and even some blood. It's not a classic, but it's still better and a lot more stylish than much of the dretch that's produced today. And it's got a surprisingly efficient and effective script. It also seems to me that "The Evil Dead" may have been influenced by this one -- a group holed up in an abandoned cabin with no phone, fighting for their lives against a supernatural entity outside.
It still sometimes turns up on the boob tube, although it's unavailable on video in the U.S. A public domain movie, it does turn up on Ebay from time to time, and it did enjoy a brief VHS release sometime in the early '80s.