Sabbatum's promising, wicked-awesome premise is Sab songs, unplugged, 14th-century style. But therein lies the rub: Sabbath established itself as a metal overlord through six-string bombast and a razor-sharp pen. The band's evil sludgery backed tales of darkness asserting infernal dominion over the earth. Translated into Latin and performed -- often in monophonic or a cappella adaptations -- via chants, lutes, fiddles, and harps, the songs lose almost all of their visceral power. Hardly a hook, nary a riff, and scant few melodies survive the treatment. If you have the background to follow and appreciate the all-too-authentic conversions, Sabbatum is probably a must-have. For the average listener, it's more akin to the Lord of the Rings soundtrack. The results are deeply atmospheric, but the songs' trip through a time warp yields the opposite of Iron Man's transformation into a murderous steel monster -- at the end of the day, they're weaker for it.