The story guide of a role-playing group is the person who designs a scenario and knows all the plots and secrets about it. In other role-playing games, story guides are called game masters, keepers, referees, or dungeon masters. Unlike most of these Role-playing games, Ars Magica is special in that it suggests multiple story guides for the same gaming group. This is possible mostly due to its highly variable pacing, which covers tactical movement as well as activities that take multiple seasons to accomplish. However, this is not a must, and many groups prefer the traditional one-versus-many setup with only a single story guide.
The main storyguide, if there are several, is sometimes called the "alpha" storyguide. He is in charge of the overall plot and direction of the saga, and coordinating the other storyguides. The other storyguides, called "beta" storyguides, typically take on specific parts or aspects of the setting, such as "The Rhine Gorge" or "The Infernal Realm", although different storyguides can still draw on these areas by coordinates with the relevant beta storyguides.