"We have 15 tracks - 13 originals and two cover songs," Mustaine tells Rolling Stone. "We did 'Melt the Ice Away' by Budgie and 'Foreign Policy' by Fear. At this point, the drums are all done and Chris is back home.

"Kiko finished all his rhythms and he's now doing solos. He's an amazing musician, very well-rounded. He did a lot of acoustic stuff, both steel-string and nylon-string, and he played a little piano at the end of a song called 'Poisonous Shadows.' It's a really haunting piece, and the part that he played is very Chopin-meets-Megadeth, if that makes sense."

Mustaine also revealed a few song titles, as well, for the follow-up to 2013's "Super Collider." "There's a song called 'The Emperor Has No Clothes,' and another called 'Tyranocide'," he says. "Several have working titles but I don't want to say what they are. After we write the lyrics they'll come."

Megadeth's storied past also seems to have also crept into the vibe of the project, according to Mustaine. "Over the years we've always said, 'We're going back to our roots'," he explains. "But the naysayers, they just want 'Rust In Peace' 20 times, which is never gonna happen. Because I've never written the same song twice.