I was playing through the level when the Dark Sun effect was to change all male allies on the map into various monster types. Instead of this, their sprites vanished and the first time I tried to attack while like that the game immediately crashed to desktop. The only thing I can think of it being besides a bug is that it tried to change my chars into a monster type that I haven't unlocked yet, but the sprite files and attack information should be in the data files so I don't see why that would cause this problem.