Regardless of the knowledge skill you’re using, refer to the rules here when making a knowledge check. Another use of the knowledge skills is for Monster Knowledge Checks. Common Knowledge: This includes the kind of general information that is commonly known about a given topic. Expert Knowledge: This includes the kind of specialized information that only an expert in the field of study could possibly know. Master Knowledge: This includes the kind of esoteric information that only a master in the field of study could possibly know.