Everything that any heavy metal band has ever done has already been done on Black Sabbath's first album. Think about it, the album has death, Satan, some LOTR shit to keep the nerds happy, Satan, hedonism, sex, etc. etc.
As if that wasn't enough, Sabbath used it's next album to elaborate on these basic themes with war, drugs, and homocidal comic book characters.
Other bands can work with the same mix. They can change things up by emphesizing Satan over drugs or mingling sex with death, but really, what's the point?
Just listen to NIB, a brilliant inverson of the Christian "lust=satan" equation. Listen to how the music is perfectly matched to the lyrics, auralizing the sound of a dark lord aroused. Than realize that your favorite childhood band did the same thing, and when you were fourteen you thought it was brilliant. then, dispair, and realize that you have wasted your youth and subsidized the wasted youths of others. Dude, all we are, is dust in the wind.