So apparently someone on the Mayhem Fest boards, who pretty much had the lineup correct the past two years, said that this would be the line-up next year.
Five Finger Death Punch (ugh, not this band again
Lamb of God
Bullet For My Valentine (see FFDP)
Side Stage Bands:
In This Moment (see FFDP and BFMV)
Job For A Cowboy
As usual, take it with a grain of salt