On the Llivnu Ku Verrta event, the adds can path though the wall if they head towards Llivnu.
It has happned a few times, however, I have been engaging them with pets since they can go through the wall as well.
This last time one of them summoned the tank while they were in the wall and he fell under the map. Not sure how the tank damaged it so far away to get summoned but he did.
I have not really figured this event out so maybe I am doing something wrong when they head towards Llivnu but I wanted it report it anyways.