I got to stage 3 goliath with full health and was unable to attack any hunters who hid where I am in the screenshot. The only skills that would damage them were flamebreath. Unfortunately this spot was also near the relay, so the support would hide in here then pop out to shoot me if I went for the relay or his teammates. Eventually all of the hunters went to this spot since they figured out I couldn’t hit them at all.
I tested in single player, and stage 1 can get in this spot just fine, but stage 3 goliath is stopped by those metal barriers. Edit: tested in single player, only lvl 1 and 2 rock can consistently damage the back wall area where Caira is hiding in the screenshot. Lvl 3 rock is too big and easily clipped / blocked by the surrounding stuff but I think there is a very small misleading area you can aim to hit.