Expedition Mysterious Damage

I am taking large chunks of damage during expeditions and I have no idea where it is coming from (I would estimate 45% of my health). I see people talking about casters that lay down circles or make asteroids or something, I specifically looked for both and saw neither. It is possible the circle was below bodies or something. Either way I moved a large distance by walking there, and then cast 1 warrior ability and before my ability started to deal damage I was hit by the large chunk, so even if I could see it, I have no idea how it is dodge-able. Maybe this is actually 2 or 3 ranged guys with perfectly synced attacks because they spawned at the same time, I really have no idea.

Not that it super matters, but I also have no idea what type of damage it is. All of my resistances are high enough that this shouldn't be an issue, but I would normally provide a value if I knew which to provide.

Tldr: If something is going to do this much damage, I need to be able to see where it is coming from.