I just spotted this thread, skimmed through it and thought "i wonder what would happen if i changed the background the dragon battle is on". So i tried it, and it crashed the game, which i thought was werid. so i looked into it. It seems like that background is somehow connected to the field script i don't know much about field editing yet but changing the background crashes the game just like changing the thrid byte in BTMD2. I haven't tried changing the monster (Dragon) in the battle but i might later on.