From the introduction: In this book you will find rules for four types of strongholds: keeps help you raise armies and improve your fighting ability, temples help you summon extraplanar allies to aid you in battle, towers let you research new spells, and establishments let you collect secrets and generate cash. Every stronghold also improves your signature class feature, powering up your Bardic Inspiration or your monk’s Ki. Strongholds grant improved class features because they draw power from the land itself. The local area around your stronghold is called your demesne (deh-MAIN). Within your demesne, your character is now, if not ruler, certainly a very important person, so the power of the land manifests itself in unusual ways in your favor. Building a stronghold also inspires people, allowing you to attract followers by rolling on a chart specific to your class. These followers could be mercenary legions or artisan peasants, foreign ambassadors or fellow adventuring heroes! Large-scale actions taken by your new army, your stronghold, or your followers sometimes take months or seasons. Also, your new abilities eventually run out of juice, after which you must return to your demesne to refresh yourself. This is called an extended rest. To support these new options, the book comes with many new systems, including rules for warfare, in which units of soldiers clash; rules for concordance, which allows any character to plead with their deity for aid; rules for creating new magic items; and rules for taking your retainers with you into combat without having to run an entire second character.