Dungeon Master’s Guide, D&D 4th edition Core Rulebook, by James Wyatt.
“The world has fallen into darkness, but great rewards await those brave adventurers willing to face the terrible dangers ahead. This core rulebook for the Dungeons & Dragons Roleplaying Game holds everything a Dungeon Master needs to create memorable adventures and grand campaigns to challenge bold adventurers.
The Dungeon Master’s Guide features the 4th Edition game rules and guidelines for creating and running encounters, adventures, and campaigns. It offers a wealth of advice to new and experienced Dungeon Masters, and includes essential game rules for awarding experience, distributing treasure, creating nonplayer characters, and adding mighty artifacts to the game.”