Spawns at -345, -0 in Crypt of Sul. Large southern room. Placeholder is "a skeletal sentinel," static mob in the middle of the room.
Fiends in the room have short assist ranges, but are immune to run speed changes and lull, so pull carefully and patiently. I was able to clear the room as a 110/24k ranger in full conflagrant gear with cleric merc. Everything hits hard, but compared to EoK trash, they're made out of toilet paper. I was able to burn the named without any trouble, even at 70% health/mana cap. Didn't log the fight, so no parse, but he didn't have the earring so I'm still here.