I am also posting this on Nez's page.
I camped Nez/Phur today on Vulak(progression server) I lost the camp once to link death, and had to restart the spawn cycle. This is a quick write up on what I did, in case anyone else is still doing these quests.
I zoned in from Frontier and proceeded to an older loc, -450, -2250. I was the only person in the zone, which meant that unfortunately there was no tracker available. Assuming that neither Nez or Phur was up, I proceeded to slowly circle out from the previously mentioned loc and kill everything in sight. This included Skeletons, Sarnaks, Giants, wurms, and gorillas. I kept my Necro box seated on the position and monitored for spawns. Once I killed the place holders, it began a spawn cycle.
I can confirm that spawns on the loc listed above (-450, -2250) approximately every 80 seconds. I can also confirm that according to what spawned on the loc, skeletons, Sarnaks, Giants, Wurms, gorillas, and wasps are all fair game to be place holders, so do not rule out ANY mob around that loc as a place holder.
In four hours of camping the loc once I had the cycle running, Phur spawned approximately one out of every ten mobs (1/10th), and Nez spawned maybe one in 25 or so at best. Nez is definitely the rarer of the two wurms, but he always dropped the red wurm gut. After about five or so Nez spawns, he finally dropped the Burning Embers.
From the standpoint of taking out the named wurms, I had a Magician and a Necromancer, and duoing them was no issue. I would say that both were easily soloable on my Magician (level 59), although I would recommend that you chain pets. Phur is a push over, and runs at 20% health. Nez, on the other hand, seems to want to nuke you till approximately 5-10%. Still, not an issue as long as you are at least half to full mana and are careful. The biggest problem at this camp is adds; my recomendation is to take along someone (Another Mage, A Necromancer, or a Shadow Knight would probably be best) in order to help out with them. While they are not dangerous in and of themselves, they do tend to gang up on you fairly quickly.
I hope this helps any Magicians or Bards in their quests. Good luck.

Bag of Scarlet Sand
Burning Embers
Crystallized Sulfur
Flame of Vox
Pearl Earring
Phosphorous Powder
Polished Gear #2
Rune of Embrace
Spell: Blizzard
Wurm Meat
Wurm Scale
Wurm Scale Coat