Slad'ran Constrictor

Located in Den of Sseratus, Gundrak (Dungeon). Summoned during combat with Slad'ran, the first boss of the dungeon. You may have to damage him a bit before the constrictors appear. They will stun you, but they always spawn in the same place and slither towards you, so one technique is to pull Slad'ran to another room to buy yourself some time.