Been raiding Droga with my guild and the only creature that dropped the circlet was the goblin bodyguard and its far more common than what many people thinks.
This is a truly great item that has saved my **** on more than one occasion. Right clickable, instant invisibility on the run? Sign me up. I use it constantly, and it makes travel for a Troll SK much, much easier. And yes, it starts working at level 20. just put it in a main inventory slot and right click. Had someone in Gfay send me a tell after they watched me disappear into the shadows as I was running. He was like, "What was that???". hehe, I love this item. Sk or necro? you need this.
The effect can be used beginning at 20th I hear, but I got it well after that so I can't verify. The item can be used from an inventory slot when not being worn like JBoots. The item cannot be activated by non SK/Necro's even when right clicking on it while not worn. You can use the effect while running.