Max Cavalera has been a professional musician since 1984 and has toured the world many times. He was a founder member of the award-winning Brazilian thrash metal band Sepultura before forming Soulfly, an immensely successful group who continue to play headline slots at the world's largest festivals and released their ninth studio album, Savages, in 2013. He also plays in Cavalera Conspiracy, the band he formed with his brother Iggor in 2006.
Joel McIver is the bestselling author of Justice for All: The Truth About Metallica which has been translated into 9 languages. He has written for Rolling Stone, The Guardian, Metal Hammer, Classic Rock, and he is the occasional guest on BBC. He is currently the editor of Bass Guitar magazine. Classic Rock magazine has called him "by some distance Britain's most prolific hard rock/metal author." He wrote the official biography of the world's biggest death metal band, Cannibal Corpse and co-wrote Megadeath's bio from bass player David Ellefson.