Exodus guitarist Holt began standing in for Jeff Hanneman in 2011 after the Slayer co-founder fell ill, and he's remained with them following Hanneman's death in 2013.

King tells Talk Is Jericho: "I already had Gary in my back pocket for any future thing. I called Gary in early 2010 and said, 'If I ever do anything, would you be into doing it?' He's like, 'Man, I was hoping you'd hit me up.' We kept it in our back pocket. There was no music - there was nothing."

King returned to the idea the next year. "The Jeff thing went down and I called Gary again," he says. "These are hard conversations, because even though Gary's my friend, I don't know…

"It's like asking a girl out to the prom, kind of. If you get turned down, you're like, 'Oh man, we suck. F***!' I said, 'Hey dude, we're going to Australia and Jeff's not going. Would you like to be in Slayer?'