The Fabled Inferno  

Got him last night. I tried something a little different from past nights but I have no way of knowing if it affected him spawning. I just made sure to keep all fire elementals cleared. killed em as soon as they popped. Because I was KOS to all elementals by now, I did end up killing other kinds of elementals. I just didn't actively go after any except fire elementals. After an hour or so he popped on the side of the island farthest from the castle. The fabled sword is droppable so it makes a nice twink weapon. Hope that helps.