I am hearing from a very credible source that LoG may infact play & the hold up on announcing everything is due to waiting on their situation. Mark Morton posted the band was not invited to play on his Twitter but most big bands on a major tour with a set announce date will deny everything.
I am starting to think several of the stages will overlap until the main stage starts.
5-18 Lamb Of God
9-05 Iron Maiden, Megadeth