A stone thrower requires a full crew to work it properly – to carry stones, push then machine round to bear on its target, and so on. If one crewman is slain then the rest can just about get by without slowing up the machine noticeably. If two or more crewmen are slain then the remaining crew will be unable to cope and the stone thrower will have to miss a whole turn before it can shoot again. This is in addition to any penalty imposed by a Misfire result. Obviously, the engine requires at least one crewman to work, so the machine will become useless should they all be slain.