The defendant in any action or suit may plead as many several matters, whether of law or fact, as he shall think necessary, except that if he plead the plea of non est factum he shall not, without leave of the court, be permitted to plead any other plea inconsistent therewith. To any special plea pleaded by a defendant, the plaintiff may demur and in addition plead as many special replications as he may deem necessary.
West Virginia Legal Code