I would say "is" because we're talking about a single group, Bloodbath, and groups are singular. To use "are", we would say "the guys in Bloodbath are...".
In Italian it's always plural, however. In fact, they must put a definite article before the group every time, which translated is like "The Bloodbath" or "The Metallica". I Bloodbath and gli Skylab or gli Anathema are the articles used. "Gli" is used for words beginning with an "s" other than "st" and before vowels. "St" words then use "Lo".
Fuckin' Italian lesson for the day. I forget the point of all this now,
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Derek, I see you're learning Czech...is it similar?