Appeared to me in the form of a shrouded willsapper but looked like a pugilist to my companion, so his appearance probably looks different to everyone. He also casts an effect on his target called Tendrils of Madness, it changes the target into the shape of a troglodyte.
The location and form of this guy as well as the other named mobs in griegs are not static. They spawn at a variety of different locations and in a lot of different shapes. So best to get a tracker if you are hunting for them or simply go through the entire zone.
if you have a map, look where it says "2nd Floor", then look all the way south at the bottom of the map and a little to the east and it pops in a little section there. was a bear and it dropped some words i can't remember, the key, and the leggings.
Possible the BEST mini Named here, very nice mid level drops. One happy warrior on the greaves, which have dropped once in about 6 kills, ring x 3, earring x 2. EASY mob, single grpable from about lvl 55, solo simple for a 65 caster of almost any class I imagine. Certainly simple for a necro.
Easy to solo, but a pain to kill. I had to kite him around the room to the north of him, which meant clearing six mobs in the previous room to make space to kite the mobs from the north room, and then FD splitting Hyraja from the mob that spawns the other side of the door and aggros if he's pulled.
After that it was a matter of keeping the north room clear and also killing the mob which spawned outside the door so it didn't add while kiting. Got one kill which dropped the ring, then placeholders, so I gave up rather than spend an evening working through more annoying trash (I want the greaves for my alt, but it's a pretty tedious camp).