The boxed set that literally blew up the Mystara setting, Wrath of the Immortals also replaced the rules for the Immortal boxed set from BECMI. When the module is done the map was forever changed. Alfheim and Alphatia were gone. Glantri lost two provinces. Thyatis is broken and most of the other nations were much worse off. This is the base breaker of the setting, with few people happy with the changes it made only a year after the Gazetteers were released.
27 апр 2018