At this point it looks like the following bands will play Mayhem Fest 2013:
Lamb Of God
Miss May I
Add in Cannibal Corpse & Chelsea Grin and you have the full line up minus the two headliners (who at this point I'm gonna guess are Rob Zombie & Deftones) unless the rumors of them adding other bands are true (other rumored bands are Megadeth, Overkill, Devin Townsend Project, Motionless In White). I have to admit the the repeating of the same bands is getting old.
5-18 Lamb Of God
9-05 Iron Maiden, Megadeth