Okay, this is pretty nuts: Thrash metal’s big four — Metallica, Anthrax, Slayer, and Megadeth — will tour together this summer during the traveling Sonisphere festival. Yeah, that festival takes place mostly in Eastern Europe, but if it’s a big enough blockbuster, they have to do a U.S. leg, right? More importantly, what’s the lineup? We know Metallica is headlining, but how does the rest shake out? [Billboard]