Stalker These guys are from Borderlands 2 & The Pre Sequel They have a gland that works as a shield as well as a cloaking device that turns them invisible until right before they attack you. Now that would be enough to irritate the piss out of anyone right? Well that's not all, they are also fast as shit so when they do turn invisible all you are able to do is keep an eye on your mini map and move around until they become visible again. They also tend to travel in packs. The good news is that once their shield is all the way down they can't cloak anymore either so all you have to I chase them until they're deed. The best way I've found to do tho is with a long range weapon (like a sniper rifle) and pick them off from afar. An Elemental weapon also does good if you have one. Shock weapons are the best choice because the shock damage saps their shield real quick.