Three things to keep in mind:
Location
Assassin PH / Loreth Soulanis: (x/y/z) -867 / 221 / -4 (East of Void zone in / North West of Pyrrdan)
(editing post to reduce confusion on location)
In game location: /loc 221, -867, -4 is where you will find PH/Loreth which uses Y, X, Z coordinates
Overview
Camp pretty straight forward, fighting on the road will surely get you adds, either Bealdurr or other roaming / spawning mobs, which seems to only occur when he spawns. Maybe coincedence, but everytime he has spawed, I have had multiple bears, snakes, wolves, and spiders join in the fun. If you get Bealdur mixed in with Loreth, you should burn/dps down Bealdurr first as he is weaker, even though Loreth is a lower level.
Battle Strategy
Loreth summons and hits really hard, thankfully slowable, but not mezzable. Not much strategy other than: let the tanks tank, hybrids and pure casters, don't get agro. Simple!
If you have no crowd control (Bard / Enchanter), then pull him towards zonein off of the road.
Additional Information
Keep in mind that if you time your spawns and don't let them roam, it's not a long wait to get Loreth to spawn, but not keeping tabs on your spawn could make this a painfully long camp.
Pulling Spot
I pulled to (/loc 121.88, -982, 17) as it seemed to be the safest spot and widely visible by people passing by.
In three hours he spawend three times, coincedence or luck? First two spawns occured within the first hour, then he was a no show for the next two hours.
He dropped the faceted earring twice followed by the mace.
Pyos
(CZ / Brell Serilis)
Edited, May 4th 2010 2:10pm by darant
Edited, May 4th 2010 2:21pm by darant
Edited, May 5th 2010 11:16am by darant

Dark Elf Parts
Elven Blood
Faceted Bloodstone Earring
Loreth's Bloodstone Earring
Obliteration Mace
Spell: Putrescence Rk. II