Book 3: The Dragon Armour introduce a different way of playing D100 Dungeon, and will give you choices much like a traditional adventure game book. It use all of the D100 Dungeon game rules from the main rule book with a few modifications. Also included are some additional rules that can be used in any of your D100 Dungeon games; whether playing a quest, campaign or an adventure. The add-on includes rules to destroy doors that are blocking your way, and rules for multi-slot armour (that protect more than one location slot). Upon successful completion, the adventurer is rewarded with a powerful advantage that can be used in subsequent games and extensions: The Dragon Armour!

Note that it is necessary to purchase the pen and pencil version separately. The Companion does not provide any of the documentation that comes with the pen and pencil version.