New zone is cool so far.
So I found the city/ruins with the big shield (Orb of Osuvox) around it. It seems if you go along the right side, the shield bugs out so it is no longer there, then will reappear.
There is no special thing you need to do, the shield just drops when you approach the frost pillar camp on the right side. You can climb the side of the snowfield and make your way quite a way inside the shield before it appears. Once it reappears you’re stuck with no way to get out except graveyard.
I took a bunch of photos to give you orientation. Shield on, shield off, inside the shield, stuck inside the shield and so on.