Here is some fresh info about Quillmane from Live EQ. I recently hunted him for his cloak both for myself and another player, and in the process, I spawned and killed close to 15 Quillmanes.
Here are the facts:
1) Quillmane is on a spawn cycle of mobs that includes:
a lion (very common)
if you have a mask of deception in your bank or inventory (yes that's right, the nerfed version of the guise) then it will block the guise
this is so bards/rogues won't get a guise when they do their hand ins.
I actually tested this with every other casino item + mask of deception and could no