They Drop Dasiron Crystals Zahlikk Crystals Ogre Blood Vanadium Ore Earthtouched Crystals Netherstone Crystals for Quest "Blurik's Toil"
hit pretty hard about 4-5k a round on my uber druid.
Easy to kite, lots of hp.
It seems the track range for these is very limited. If you don't see any on track just run around and you will find them once you get close. There seem to be 4 of them on the level. 2 on the west side of the big hall and 2 on the south side. I haven't done an extensive exploration but they repop pretty fast.
Don't kite them out in the middle of the big hall, they have mobs that will assist them, I didn't have any problems kiting them amoungst the mobs around the outside edge of the big hall.