According to the April 2009 issue of Revolver magazine (see cover image below) — the official Rockstar Energy Mayhem Festival media partner — Massachusetts metallers KILLSWITCH ENGAGE are the "special-guest" act that will perform on this summer's Rockstar Energy tour.

This year's Rockstar Energy Drink Mayhem Festival trek will be headlined by SLAYER and MARILYN MANSON, with KILLSWITCH ENGAGE also making an appearance on the same stage (along with Welsh metallers BULLET FOR MY VALENTINE). The Jägermeister stage will feature TRIVIUM, ALL THAT REMAINS, GOD FORBID and the Jägermeister Battle of the Bands winner; the Hot Topic stage will feature extreme metal bands CANNIBAL CORPSE, JOB FOR A COWBOY, BEHEMOTH, THE BLACK DAHLIA MURDER and WHITECHAPEL. The World's Greatest Freestyle Motocross team METAL MULISHA will also be revving up the crowd with their unique style of death-defying motorcycle stunts on all dates.

The festival billing is as follows:

Main Stage:

SLAYER
MARILYN MANSON
KILLSWITCH ENGAGE
BULLET FOR MY VALENTINE

Hot Topic Stage:

CANNIBAL CORPSE
THE BLACK DAHLIA MURDER
JOB FOR A COWBOY
BEHEMOTH
WHITECHAPEL

Jägermeister Stage:

TRIVIUM
ALL THAT REMAINS
GOD FORBID

KILLSWITCH ENGAGE is apparently unable to officially announce its participation in the Rockstar Energy Mayhem Festival due to the band's involvement with the Music As A Weapon IV tour this spring.

The Rockstar Energy Drink Mayhem Festival is the brainchild of Kevin Lyman, John Reese and CAA's Darryl Eaton, the creative team behind some of the industry's most successful road jaunts, including the long-running Vans Warped Tour and the worldwide Rockstar Taste of Chaos Tour.