Cast Illusion Wall on three squares in the MP Streams of Blood map. The third square was a stream, and the wall did not appear there, allowing an opponent to attack me through that square.
Good to know. Seems a bit odd, but I suppose with the way terrain works, building a wall there would actually let folks move through that space, eh? Same issue for Wall Of Stone?
It would be kind of hilarious if Wall of Stone turned impassible terrain into open terrain, as if the spell was creating a stone bridge to walk over... lol