Yep dropped off same mob for me. Was located where I have also seen the enraged emissary (or enraged somethingorother anyway) spawn, in the center wall position of the room at the end of the journey into the caves if you turn right at the tentacle bridge.
Are you referring to the right turn in the middle of the bridge? i.e., the same tunnel that leads to the Enraged Soulstealer? If so, is he in the second (furtherest) room? Thanks