Black Sabbath's first studio album with Ozzy Osbourne in 35 years, the making of 13 was unsurprisingly not without its challenges: guitarist Tony Iommi was undergoing cancer treatments throughout, Osbourne maintained his long-suffering battle with alcoholism, and original drummer Bill Ward opted out over contractual disputes (Rage Against The Machine's Brad Wilk filled in). Nonetheless, at producer Rick Rubin's Shangri-La Studios in Malibu, Sabbath – which includes bassist Geezer Butler – crafted one of its hardest-hitting LP's since its early-Seventies heyday. "We had to unlearn everything," says Butler. Adds Iommi, "I'm still here and it's okay. We had to do this album now."