Atlanta-based heavy-metal group Mastodon joins a slew of headbanger bands at MAYHEM FESTIVAL Tues., AUG. 12. Rockstar Energy Drink is hosting the havoc and Lakewood Amphitheatre will break out two extra stages to accommodate performances by Slipknot, Disturbed, Dragonforce, Underoath and Machine Head. Need some reassurance about just how hardcore the music will be? Slipknot's Sid Wilson broke both of his heels when he jumped off a stage at Mayhem's first show in Seattle. $28.50-$56.50. 10 a.m. 2002 Lakewood Ave. 404-249-6400. www.livenation.com.