The best place to test this out is with the Sisters of the Sacred Valor, or something like that. The mission where you are facing endless numbers of chaos demons, and artillery strikes are coming down every minute, and you have about 10 of them total before the mission is over. You are trying to get vengeance points.

There's tons of rubble and destroyed buildings, and with the artillery strikes and other AoE going on, the walls will crumble. Unfortunately they don't actually disappear, the are just invisible. If you play with mouse movement disabled, and use keyboard keys, or even a controller if you're crazy enough, you will find yourself in situations where you seem trapped.