Among '80s headbanger gods, Switzerland's Celtic Frost is the only one that can be called arty. Granted, it's an odd tag for the singular — and sometimes symphonic — seminal sludge that influenced countless black-, death-, and thrash-metal groups. But before they settled on the Celtic Frost moniker, the guys played as Hellhammer — an evil-obsessed coven that mined the genre's underground for sounds. This two-disc compilation gathers a trio of oft-bootlegged demos from 1983. Newly remastered, the dungeon tapes sound cleaner than ever while retaining their grit. In songs like "Bloody Pussies" and "(Execution) When Hell's Near," frontman Tom Gabriel Fischer and guitarist Martin Eric Ain conjure tones that recall iron files scraping against battle-ax blades. All punk speed and metal clunk, some of Demon Entrails' tracks come off as sloppy Venom-worshiping sessions. Others, however, stand as worthy companion pieces to Frost's landmark 1984 album Morbid Tales.