Discussed a bit under the "Bolting Invisible Monsters" bug, but I thought I'd make this a separate one since the two effects aren't quite the same...

Bug is that essentially monsters that cannot see under darkness will not fight back if attacked by the PC in any way if both the monster and the PC are in darkness. As a result, many powerful monsters can be killed without any risk, including shopkeepers, the great water dragon, and the snake from beyond. The only situation under which the monster will fight back is if the PC leaves the darkened area, or they panic and there are no other possible places to move other than the square the PC is standing on.