over the previous edition. The effects of a character's strength score on hit probability, damage, weight allowed, and open doors rolls were changed. High intelligence conferred an increased chance for both spell knowledge and ability to learn languages. A high wisdom score now gave clerics a spell bonus, while low wisdom gave a chance of spell failure. New charts delineated the effects of constitution, dexterity, and charisma. Each of the five main character classes and five sub-classes had its own experience table; for most classes it was now harder to gain promotion above third or fourth levels. Multiclassed characters were also introduced. Unearthed Arcana added the Cavalier, Barbarian, and Thief-Acrobat classes. Dungeons & Dragons Basic Set The second version of the Dungeons & Dragons Basic Set combined the idea of race and class; non-human races did not have classes. Hence, a character might be a (human) Cleric or else simply an "Elf" or "Dwarf". The Basic Set presented four human classes: Cleric, Fighter, Magic User and Thief, and three demi-human classes: Dwarf, Elf, and Halfling. The Companion Set introduced four optional classes for high-level characters: the Avenger, Paladin, and Knight for Fighters, and the Druid for Clerics. The Master Set introduced one additional class: the Mystic. The Rules Cyclopedia included in its final pages instructions on modifying the Halfling class into a Gnome class, adding that as an option. The Gazetteer series included many optional classes for humans and non-humans, including the shaman (GAZ12) and shamani (GAZ14). Additional human and race classes were also presented in other supplements. Advanced Dungeons & Dragons 2nd edition The 2nd edition of Advanced Dungeons & Dragons attempted to streamline what had become a hodgepodge of rules that only applied in specific cases in 1st edition. As such, it sought to simplify the rules and straighten out contradictions. Character classes were divided into four groups or "metaclasses": Warrior, Wizard, Priest, and Rogue. Each of these groups had a "base" class which only required at least a 9 in the "prime requisite" statistic in Fighter, Mage, Cleric, and Thief; these were intended to be playable in any setting. The Player's Handbook went on to say that "all of the other classes are optional." Each group of classes had the same hit dice (determining hit point growth), THAC0 progression, and saving throw table. 2nd edition maintained minimums in certain statistics to qualify for some classes, but removed