This year's lineup is headlined by Rob Zombie, who played the festival in 2010 and is a veteran of a certain U.S. metal tour that preceded Mayhem. "It's pretty similar to the Ozzfest," he told Radio.com, referring to the Osbourne-led affair that led metal bands across America in the late '90s and early '00s. "It's a lot of the same bands."

But not all of the same bands. Where Ozzfest reached out to include nu-metal and rap-metal hybrids like Limp Bizkit, Hed PE, Tommy Lee's Methods Of Mayhem, Crazy Town and Linkin Park, Mayhem appeals more to metal purists (though nu-metallers Korn have played both festivals).

Still, Bill Kelliher of Mastodon also notes the similarities between the tours; his band, an Ozzfest alumni, returned to Mayhem this year after playing the tour's inaugural trek in 2008.