Maybe Righteous Fire boys just get some extra tankiness? Definitely a weird one. Chieftain definitely comes to mind with the free +100 fire resist, but outside of that I can't see anything besides your aforementioned Doryani and OG Nebulis maybe. Run a purity of X really high, get to 92 resistance and you're looking at something like 255-340% increased cold and lightning damage. That's pretty bigly. I'm thinking we see some Storm Callers with that oneshotting bosses. And, of course, lightning ball boys mass clearing easily.
Edit: well fuck me, the way it's worded it's not matching # to #, it's just going to take it from the top resistance. Like a reverse The Admiral. So dunno, Doryani's for sure and maybe not much else. Could make gearing for high-unique classes easier perhaps if they've got the right synergy on resists.