While fighting a large group of enemies in Act 2 Normal, some of them used an ability that created a circle on the ground, with a sort of green, swirling vortex pattern in it. I didn't get a screenshot before they disappeared, and I haven't seen this effect since.
My first thought was "green = poison", but it didn't seem like I took any damage from standing in them.
What is this effect? Is it unique to a particular monster type? Or a random elite monster ability?
Best Answer
It is caused by any monster with the Plagued attribute
It does damage over time if you stand in it. The damage is negligible on Normal, however you will not want to be standing in this at higher difficulty levels.
In addition, the circles can stack on top of each other. I know this from experience where I can safely stand still and tank some Plague monsters, however over time they'll add more stacks of the green void to where I am standing and eventually it will be doing insane amounts of damage per second, so I'll need to move to a new spot :)