Just some notes as I finally go around to going back and doing ToL for some alts:
After some tooling around, I noticed that "a forgotten aberrant" (tegi/alien models) shares spawns with "an erased hero's guard" (shade models). I believe there are seven total. I hung out north of the torch and avoided any other mob name/type in the area. Quietus spawned from this rotation. I am unsure if one of these is a key ph mob like many of the ToV/CoV named, but it doesn't matter, just clear 'em all.