This is a darn hard achievement because the nameds are hardly ever UP on their own. I like to complete older zone hunter achievements by porting in, checking TRACK and tracking down and slaying any nameds that happen to be up. This achievement requires visiting 3 separate zones and the nameds are almost never UP. In 30 or so visits, I've seen 5 out of about 30 nameds. I finished Resplendent Temple in fewer visits and that zone has about same number of nameds. And on FV I never see any other players in those zones so it's not like I'm competing for spawns.
Usually I can kill 90% of the nameds in an older zone this way and when I'm down to 2-4 needed, I will slay all the Phers and then come back in an hour or so and sometimes get lucky. It's a fun extra little task I do after my daily Lesson/tasks. But doesn't seem to work for Sepulcher! Guess I've have to wait for a bonus spawn event...
Edited, Aug 26th 2018 9:54am by Sippin