Through The Book of Immortals, characters will face tests and trials deemed impossible by mortals as they work their way towards ultimate power. They begin to deal with the gods as equals, interacting with good and evil, law and chaos, in their primal forms. They make bargains with celestial beings, play devils off against one another and may even develop a cult dedicated to their deification.

The Book of Immortals contains:

• An introduction to the rules, covering terminology and differences between an Immortal and a high-level character.
  
• Wellsprings, which details the effects of tapping into the universe's hidden power sources.
  
• Covenants addresses those Immortals who derive their powers through agreements with other creatures.
  
• Gifts allow the Immortal to use the might derived from powerful artefacts for his own ends.
  
• Challenges outlines the various tests and trials Players face along their path toward transcendence.
  
• The Immortal World, provides details about the complex world of Immortal politics.
  
• Aspiration to Transcendence presents six established paths of immortality.
  
• Immortal Characters gives complete statistics for three Immortals at varying stages of immortality.