In role-playing games, the types of magic-users are more delineated and are named so that the players and game masters can know which rules apply. Gary Gygax and Dave Arneson introduced the term "magic-user" in the original "Dungeons & Dragons" as a generic term for a practitioner of magic (in order to avoid the connotations of terms such as "wizard" or "warlock"); this lasted until the second edition of "Advanced Dungeons & Dragons", where it was replaced with "mage" (later to become "wizard"). The exact rules vary from game to game. The wizard or mage, as a character class, is distinguished by the ability to cast certain kinds of magic but being weak in combat; subclasses are distinguished by strengths in some areas of magic and weakness in others. Sorcerers are distinguished from wizards as having an innate gift with magic, as well as having mystical or magical ancestry. Warlocks are distinguished from wizards as creating forbidden "pacts" with powerful creatures to harness their innate magical gifts.