Any of those Flying mobs garg looking mobs in the middle open area. there are 3 ramps that go to 3 platforms in the middle of zone in the open area. Any of those gargs on top of there or under it can be PHer. tricky pull spot tho. Good camp is inside those doorway where Excrud will spawn
EDIT just confirmed PHer as well with Miskanzi post
Rotting of Thel - Skeleton illusion with slow, snare, 40k DoT, 10k Mana/Endurance DoT. If not cured, triggers a 400k DD when it fades. Infection of Thel - Zombie illusion with slow, snare, 20k DoT, 5k Mana/Endurance DoT. If not cured, triggers a 400k DD when it fades.