The House of Seven Corpses (1973)
A director making a horror movie based on seven mysterious deaths in the history of the well-to-do Beal family decides to film in the actual mansion where the deaths occurred. The family were allegedly involved in the black arts, and the film crew discover several occult reference books in the house. The director decides that to make his film more authentic he'll replace the incantations in his script with actual incantations from one of the books. It won't come as a surprise that this isn't a great idea; as one particular incantation is being recited, two decaying hands emerge through the earth of the Beal family graveyard in the mansion grounds...
It's low budget, but it does have the always great John Ireland as the film's director, as well as John Carradine as the mansion caretaker, whilst former 1950's noir and sci-fi glamour girl Faith Domergue plays a faded star now reduced to B movies. There are several meta touches, including some of the 'cast' of the film-within-the-film doubling as crew - as some cast-members of The House of Seven Corpses did for real. The dialogue takes some nice snipes at actors' egos and unreliability, and the film business in general (I'm sure there are more in-jokes that only those in 'the biz' would get). The lead performances are good, the location (actually the Utah Governor's Mansion in Salt Lake City) is great, and the movie does a good job of building atmosphere. The downside is that 1) other than an opening credits montage, we have to wait an hour before the first kill (not counting a cat!), and 2) the admittedly creepy ending is nevertheless confusing as hell (I see online I'm not the only one who thinks so!). But it is an entertaining watch. 6/10