Haku mision what just killed me

Were they the zombies that drop poison clouds on death? I've had a few mobs stack poison damage over time on me and my hp always decreases extremely fast even though I have a decent amount of chaos resist.

They could have been but I died so fast each time I didn't even notice the greenish clouds. I've run into poison clouds before as well countless times, and would take about 6-7 secs to reduce my health to 0. This was less than 2 seconds.

Perhaps if it was poison clouds combined with the poison on hit mod, but still not sure it would knock off almost 5k hp that fast.

Whatever it was, if I Ever see a poison on hit on another Haku mission, I'm running right thru and hoping I dont get hit with my max blok chance :-)