Sabotage is the final release of Black Sabbath's legendary First Six, and it's also the least celebrated of the bunch, though most die-hard fans would consider it criminally underrated. The band continues further down the proto-prog metal road of Sabbath Bloody Sabbath, and this time around, the synthesizers feel more organically integrated into the arrangements. What's more, the song structures generally feel less conventional and more challenging. But more than the compositions, the real revelation on Sabotage is Ozzy Osbourne, who turns in his finest vocal performance as a member of Black Sabbath. Really for the first time, this is the Ozzy we all know, displaying enough range, power, and confidence to foreshadow his hugely successful solo career. He saves the best for last with album closer "The Writ," one of the few Sabbath songs where his vocal lines are more memorable than Tony Iommi's guitar parts; running through several moods over the course of the song's eight minutes, it's one of the best performances of his career, bar none.