On its sixth album, Brazil's most famous head-banging outfit takes a page from the nu-metal book but, more importantly, combines its brutal thrash-metal sound with indigenous music from its homeland, occasionally utilizing the percussion and chants of the country's Xavantes tribe to powerful effect. The biggest standouts are the lively, acoustic-guitar-driven "Itsari" and the epic closer "Canyon Jam," both improvisations with Xavantes musicians that make for welcome contrasts to the record's intense bombast. Elsewhere, Brazilian percussionist Carlinhos Brown drives the rhythm-laden "Ratamahatta," a track that exemplifies the quartet's distinctive brand of "tribal metal." ROOTS marks a big step forward for the thrash-metal genre because of the way Sepultura matches its carefully controlled mayhem with the dynamic nature of its influences and collaborators. Faith No More singer Mike Patton, Korn frontman Jonathan Davis, and Limp Bizkit's DJ Lethal all pop up on "Lookaway," a dark, grinding tune with Eastern-inspired vocals. As a whole, ROOTS is a visceral synthesis of groove and aggression, especially when drummer Igor Cavalera lets loose with flurries of tom-tom fury. ROOTS also closes a major chapter for the group, since after recording the album, vocalist/guitarist Max Cavalera departed to form Soulfly.