I saw these guys (Holy Grail) open for Amon Amarth back in the day and had no idea who they were other than they were the remnants of White Wizard (also good). Most metal shows have a "big" headliner and a few piddly bands or locals that open for them, but these guys got on stage and MELTED it, almost upstaging AA. The first note the singer hit grabbed our attention and didn't let go until the set was over.