This is a poison cloud type trap that spawns randomly in specific areas of the zone. I am a monk and been pulling all around these traps. I cannot see any visible effect otherthan the emote I get when I run close to the traps.
I had an elite group here, these are at the son group... we had killed every single mob around including the direwind current and it seemed more and more seemed to spawn... I suppose if you kill a certain amount of mobs in a certain amount of time maybe it triggers an event something somewhat similar to Tiorpat Tornwing in RCoD... just a thought.