The music world is mourning the loss of Slayer guitarist Jeff Hanneman, who died yesterday from liver failure brought on by apparently not related to the rare skin disease called necrotizing fasciitis that Hanneman developed following a 2011 spider bite. He was 49.

I don’t think it’s a stretch to call Jeff Hanneman the heart of Slayer, as much as any member of that band can have an individual persona outside their collective window-battering sonic monsoon. Jeff was a guy who seemed to love what he loved unabashedly. Case in point: he plastered Oakland Raiders stickers on his guitars next to emblems from punk bands who wouldn’t be caught dead outside a football stadium. Of course, that’s the kind of move Slayer is famous for, blending the raw fury of punk with even angrier outposts (Jack Tatum was colder than anyone in D.R.I. and you know it).

More importantly, Jeff Hanneman played with such heat and ferocity you just knew he was putting in his all. I’m not trying to make this about me but when I look back at some of the ways I’ve described the basic sound of Slayer in the past—“turgid cascade of sadism,” “[sounds like someone] being ripped apart by a pack of wild dogs”—who else could evoke such responses but Slayer? Jeff Hanneman was obviously a huge part of that. He helped define speed/thrash metal, he did it with a tremendous amount of passion, and for that we’ll always miss him.

EDIT: After checking out various obits for Jeff online I think this open letter from Slayer, posted a year and some change after the initial spider bite, is the best item to read to get a sense of what his illness was like.