Metallica's 1988 track "Blackened" is easily one of their heaviest songs, but Denis Pauna made it different in a whole new way. Check out Pauna's death metal rendition of "Blackened" above and try not to break your neck headbanging.
If you're looking for more death metal Metallica, Pauna mentioned in the comments of his video "I'm working on full And Justice for All album in death metal style and it will be out this month." And yes, we'll be posting about that too because it'll probably rule.