Hey Ian For one of my maps, I've got a boss unit trapped behind a structure that dies after some rounds because I couldn't think of any other way to have it come into the battle after x rounds have elapsed. Unfortunately, when I made that unit flying, it was able to fly right over the structure and coming into the battle much sooner than it should. I really want this unit to fly as it makes him much more difficult to kill. I've thought of making the tiles around the unit a different terrain because of not_flying and giving this unit a skill that changes terrain types but I'm not sure how I would get it to target the proper squares at the right time. Can you make not_flying a valid flag in units and structures so that flying units can better be imprisoned? Dickson