Eric of Amber used it to decimate the armies that marched against him. Princes of Amber on their deathbed can pronounce a curse that always comes to pass. Everything exists somewhere in shadow. Oberon, who was King in Amber, is not quite as dead as everyone thinks he is. The Courts of Chaos exist at the opposite end of reality from Amber.
Alliances are common and betrayal just as common.
Amber on your own. You really do need to read all five. Fortunately none are particularly long and they read quickly. There is a second Chronicles as well, consisting of yet another five books, but they are not present in this volume. They also have a different protagonist and consist of completely different events.