A mostly ambient & quiet film {almost ASMR sometimes} for a Metal-based movie set in the forest. A local Black Metal band who also happen to be a cult residing in a catacomb-like dwelling, runs like a bearded darkryst-like figure named "Black Monk", with a couple of girls and the band as veritable "apostles" who spend the days drawing, writing lyrics, drinking, & "working" {practicing}. They are hiding out from some former 'occult crimes' involving sacrificial rites.
A local girl develops an infatuation for the vocalist, while another girl is pregnant and lives with her mute grandma, who are both also hiding out from the Metal Cult. Overall, The Cult make their way with the help of a secretive guide {with the Absurd backpatch}, who is himself dispatched in a remarkable bloodlust scene.
Finally at the ceremonial grounds once the pregnant girl and grandmother are captured, she's literally crucified as grandma undergoes immolation, thus epidermal ecdysis revealing the serpentine demon. Her 'desire' reminiscent of a common prerequisite for skinwalkers, then taken to Hell like Don't Break The Oath.
Further cleverly amusing references to Grandma {KD Them / Conspiracy}; the Nuns Have No Fun ep to be the method of execution; one of the members suffering cranial vulnus sclopetarium like 'Dead' of Mayhem while wearing the eponymous shirt. Not to mention the very title of the film is named after the landmark Venom album by the same name!
Some noted shirts spotted are Mayhem, Mercyful Fate, Bathory, & Burzum. But surprisingly no Sepultura?