To the casual heavy-metal fan, finding headliners for the annual Rockstar Mayhem Festival probably seems like a simple task.

Just pick up the phone and call Metallica. Or Judas Priest. Or Iron Maiden, right?

Wrong.

It’s not that easy. In fact, the 26-city MayhemFest tour hasn’t even started this summer, but event producer John Reese already is trying to figure out the perfect band lineup for next year’s festival.

“That’s the $64,000 question right there, is how we book it,” Reese says. “You have to stay true to the fact it’s a heavy music festival, but you also have to sell tickets. That’s our biggest challenge.”

In its fifth year, MayhemFest is bringing back bone-rattling veterans Slipknot and Slayer — two major bands that have headlined previous MayhemFests.

Why back so soon?

“There’s not a ton of huge-drawing heavy music bands out there,” Reese explains. “So there will be some recycle of artists that have played it before that we bring back. But that’s because there’s probably 20 to 25 bands in the world that could be one of the top two artists on this package.”

Slipknot and Disturbed headlined the first MayhemFest, which was launched in 2008 to fill the void left after OzzFest called it quits. Slayer and Marilyn Manson topped the bill in year two. Korn and Rob Zombie headlined year three, which was the first time MayhemFest visited the Treasure Valley. In 2011, MayhemFest delivered a trio of headliners: Disturbed, Godsmack and Megadeth.

Besides Slipknot and Slayer, the acts at next week’s show will be Motorhead, Anthrax, As I Lay Dying, The Devil Wears Prada, Asking Alexandria, Whitechapel, Upon a Burning Body, I the Breather, Betraying the Martyr, Dirtfedd — and Boise band Karin Comes Killing.

With music starting at 12:30 p.m. and running until 10:30 p.m., it will be a cranium-crushing marathon.

When economic times are tough, Americans seek out entertainment as a form of escape, Reese says. No form of music offers escape better than metal — at least for the tattooed, mostly male fans who treat it as a way of life. Consequently, organizers expect 8,000 to 9,000 fans at the show July 4 — and even larger crowds at other stops on the tour.

“This is going to be our biggest year ever,” Reese says.

MayhemFest will feature three stages, including a beefed-up secondary stage this year. Sid Wilson of Slipknot will DJ between acts. And high-flying motocross riders Metal Mulisha, who have been part of the MayhemFest experience since year one, will entertain by doing crazy backflips.

“The fans seem to love that,” Reese says.

Eagle promoter CTTouring had envisioned a fireworks display to celebrate the Fourth of July. That isn’t going to happen after all. But you’ve got to expect a few heshers to set off firecrackers in the parking lot — if not launch a bottle rocket or two over the mosh pit during the show.

The true fireworks undoubtedly will be on stage. A Slipknot performance, in particular, is not a subtle experience. That’s why the bludgeoning, mask-wearing band fits in so well at MayhemFest. It’s an event aiming to “(bleep)ing slap you over the head and knock you upside your head fast and hard,” Reese says.

In other words, it’s all about giving the testosterone-fueled audience exactly what it wants.

“If you develop something — even with a (lousy) economy — that people are excited to see, and you price it right, they’ll come,” Reese says. “And that’s what we try to do.”

Michael Deeds: 377-6407, Twitter: @IDS_Deeds