The idea arose in February, when it was confirmed Hammett would guest with Exodus on stage at his Fear FestEvil event, and said it would be a "great idea" if he was invited into the studio with them.

He tells Rolling Stone: "It felt really casual, really cool - just it did back in 1980 when we were all hanging out." He adds: "Recording a solo on their album was a huge thing for me. Other than the demo that's been heard by a lot of people, it's the only time I've ever recorded with Exodus."