W. Va. Code § 56-4-21
To any declaration or county on a policy of insurance, whether the same be in the form prescribed by section seventeen of this article or not, and whether the action be covenant, debt or assumpsit, the defendant may plead that he is not liable to the plaintiff as in said declaration is alleged. But if in any action on a policy of insurance, the defense be that the action cannot be maintained because of the failure to perform or comply with, or violation of, any clause, condition or warranty in, upon or annexed to the policy or contained in or upon any paper which is made by reference a part of the policy, the defendant must file a statement in writing specifying by reference thereto, or otherwise, the particular clause, condition or warranty in respect to which such failure or violation is claimed to have occurred, and such statement must be verified by the oath of the defendant, or some other credible person, to the effect that the affiant believes the matter of defense therein stated will be supported by evidence at the trial.
W. Va. Code § 56-4-21