When it comes to musical collaborations, you never can tell what will happen. Ronnie James Dio’s previous work with Black Sabbath produced two fine studio albums, one “Heaven & Hell”, is usually rated by fans as one of Sabbath’s best. After leaving the group, Dio went on to a long and successful solo career. Long hailed as one of metal’s most powerful vocalists, Ronnie rejoined his former bandmates to produce an under appreciated metal masterpiece. Dehumanizer, is a powerful collection of music, with minimal filler material. Compared to Sabbath’s recent recordings featuring Tony Martin’s vocals, the music here definitely has a harder edge. Dio has ways been acknowledged as an outstanding songwriter. His contributions in that department take the level of quality of this recording above the typical Sabbath effort. No other Sabbath vocalist could give us songs like “I”, “Too Late”, and “Master of Insanity”. Tony Iommi, a heavy metal legend and creator of dozens of classic riffs, seems truly reborn here. His playing, while maintaining his signature tone seems to be exploring areas he has not been in before. The riffs are some of the best he’s come up with in some time. The tone is raw, with some wide mood and tempo swings. “After All The Dead” is slow number, the opening notes of which just drip evil, setting up a heavy groove. “TV Crimes” is “speed Sabbath”, played at an upbeat tempo favored by Ronnie in his solo work, the song rocks, and has a killer Iommi solo. “I” is a powerful heavy duty number featuring major wah wah usage. “Master of Insanity” has an “electric” edge, and a pounding groove that suits Dio storytelling vocal style. There are also two versions of the powerful song “Time Machine”, both are great, but the Wayne’s World version seems tighter, and the lyrics work better. Geezer Butler’s bass is not particularly prominent in the mix. And Vinny Appice’s drumming is serviceable rather than flashy. So Ronnie Dio and Tony Iommi really do dominate the sound. Will Dio ever team with the Sabs again? Who knows? What can be said is that this particular short-lived reunion produced one of the heaviest and best Sabbath recordings ever.