Every path on the album features a different guide singer including Lemmy, Max Cavalera and King Diamond. Grohl approached death metal legend Chuck Schuldiner of Death, who was at the time battling brain cancer, to contribute to the project, and still campaigned to raise money to help Schuldiner pay his checkup bills, but Schuldiner succumbed to the disease previous to some collaboration could occur. Soundgarden guitarist Kim Thayil theater extra guitar on Ice Cold Man and Sugary Dreams. The book artwork was shaped by musician Absent (Michel Langevin) of Voivod. O.

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