They also played the main stage at Ozzfest 2006 alongside bands such as DragonForce , Lacuna Coil , Avenged Sevenfold , Disturbed , and the co-headliners System of a Down . Immediately following this European tour , they played the main stage at Ozzfest 2006 alongside DragonForce , Lacuna Coil , Avenged Sevenfold , Disturbed , and co-headliners System of a Down .