I'm camping this guy right now.
Location is: -3000, -215, -248
This is inside the rat & spider caves in Plane of Disease. Enter the caves and keep left from the first chamber. Once you reach the second chamber the place holder (a bubonian relak) is located immediately on the left standing in front of a large rock (looks like three rocks together).
The respawn time appears to be around 18 minutes.
Edited, Feb 9th 2022 10:31am by MagusSareb