It looks like a minor Dario Argento rip-off that might have played at second-rate grindhouses and a few Midwestern drive-ins around 1976. We would have totally went and seen that movie.Something about the twin bird/snake faced sisters with the tentacular hair is quite fetching. And their zombie/vampire guardian/buddy down below is just a nice bonus.
Now, the layout of the text more or less destroys the movie poster illusion, but we forgive it because it actually works quite well as concert flier text, which is what it actually is. The colors are also just about perfect. All told, another great flier.