These lovely shadowed-man-like mobs spawn as part of the new hotzone quests.
Now, it may just be me... but don't dabble with them lightly if you are a casual solo type. The spawns in the Steppes kill my level necro pet in a couple of hits (with a cleric merc out) and I am level 71.
I got eaten by one in Plane of Disease when I aggroed it amongst my swarm-farming for an attempted quest piece.
They do despawn rather quickly if you leave them alone (they don't appear to aggro... conned threatenly to me in the Steppes).
Just a heads-up to anyone that is more casual and/or unguilded. The final result of the Skal's quest appears to be decent.
BTW, the Plane of disease aug is a "lump of pus" (or close to that --don't have it on me at the moment) and the Steppes one is Portal Scrap
Edited, Dec 18th 2011 9:34pm by snailish