More than 20 metal bands will appear on the Sounds of the Underground Tour (search) this summer, bringing earsplitting music and bone-chilling guitar riffs to amphitheaters and arenas across the United States.

The Virginia-based "American death metal" band Lamb of God (search) will headline, but the band to watch seems to be the satirical thrash metal band GWAR, whose messy stage shows, theatrical antics and shock-rock reputation precedes them at every show.

"I haven't seen GWAR (search) since I was fourteen. (They are) a cross between space aliens, Transylvanian ghouls and sex freaks costume-wise," said Poison the Wells guitarist Ryan Primack. "I saved my shirt. You're supposed to wear a white shirt and you're supposed to save it." Adventurous fans will have the opportunity to have putrid liquids and curious, unidentifiable matter thrown on them as GWAR appears for halftime performances throughout the day at each tour stop.

Also coming back to the United States with a fanatical following is the Swedish progressive rock/death metal band Opeth (search), known for their technical prowess and mind-bending epic songs.

Bands such as Poison the Well, Clutch, Opeth, Throwdown, Every Time I Die, From Autumn to Ashes, Norma Jean, and Unearth are part of the lineup; performances begin at 11 a.m. daily.

"I just want to know how they're gonna clean up in between shows," said Throwdown's frontman Dave Peters. "We'll probably be playing in a pool of mayonnaise."

The soon-to-be annual event, which kicks off June 25 in Lowell, Mass., is a showcase for up-and-coming as well as established metal and hardcore bands.

"It's gonna be a silly, incredible hardcore summer camp," said Lamb of God vocalist Randy Blythe.

Blythe's advice to fans?

"Bring some Band-Aids and ear plugs."