The Game Master's Guide is one of the two core books for the Second Edition of the Legend of the Five Rings roleplaying game. Unlike the other editions of the game, the Second Edition was split into separate volumes for players and the GMs. This edition also alters the basic mechanic so players roll a number of dice equal to the skill, instead of their skill trait. From the back cover:

You say that Honor is a force more powerful than Steel?
Prove it.
In a land consumed by dark magic, honorable samurai and spell-wielding shugenja must forge a new path toward the future... for the sake of an ancient Empire.

Revised and updated, the Legend of the Five Rings Game Master's Guide contains everything you need to create your own Emerald Empire! Within these pages, you will find everything from monsters to natural disasters; from the provinces of the Empire to the dangers of the Imperial Court. Discover your own adventures within the world of the popular Legend of the Five Rings collectible card game.

The Game Master's Guide includes:

• Easy to get started: Complete information on provinces, new maps and charts, and easy-to-find information on the length and breadth of the Emerald Empire.
  
• Culture and History: Choose your time period -- before or after the Clan War -- and prepare to be immersed in one of the richest and most detailed game worlds ever created!
  
• The Shadowlands: Complete information on the most dangerous realm in the Empire, including details on the Taint, the creatures of the Dark God, and the secrets you will discover beyond its dangerous borders!
  
• Extras: Dozens of charts, creatures statistics, and a ready-to-play adventure: "The Haunting of Usagi Castle".