Adler is a massive fan of the thrash icons and even had Mustaine sign his album collection when the bands toured together years ago. But despite that, he admits he hesitated when offered the chance to record, because he knew of the mainman's reputation as someone who makes all the choices himself.

Adler tells Revolver: "I expected it to be a a 'do what you're told' kind of situation. At the same time I'm thinking, 'He could call anybody else that could do what they're told. There's a reason he's calling me.'

"I thought, 'If I can't contribute and I'm being told what to do, and I don't like the material, this is a bad move for me.'" So he took the initiative at the earliest moment possible. "I took one of the demos and I said, 'Here's what I'm thinking about the beginning - I'm not sure about this one little part. Maybe we could speed it up, or chop it off.'