All on the cello. Pretty nuts stuff. Apocalyptica started out just the strings, adding drums, and even vocals later - and are fab in their songs too btw. Great live band I can also attest to, and here is a cover of a Master of Puppets classic

Lighter string actions until the breakdown, with the vocals being played very upper register. But when that palm muted riff kicks in the cellos go all bassy distorty, and the harmonies for the guitar solo are just sublime. Definitely many tracking loads of dubs and overlaying plenty to give amazing depth

Happy Monday!