From the introduction:
"The third in the ‘Classic Play’ series from Mongoose Publishing, The Book of Encounters & Lairs covers a field of central importance to any d20 game in unprecedented depth and detail. This series forms a collection of definitive works on subjects relevant to any gaming group.
It is going to happen sooner or later. For many gaming groups, it happens all the time. The characters are going to wander out of the safe places of the world and go looking for trouble. They will pack up their things, kiss their loved ones goodbye and head into the ‘great unknown’.
For the prepared Games Master, this is not a problem. There are hundreds of creatures and thousands of situations that can be encountered while travelling. If the Games Master has planned ahead of time, setting up what befalls the party is as easy as getting out the dice.
Unfortunately, this level of preparation is almost impossible to achieve on a constant basis. Players, being players, have a distressing tendency to step outside the boundaries of any given plot line. That is where The Book of Encounters & Lairs comes in. Within these pages, Games Masters will find encounter tables, pre-made scenarios for a variety of monsters and pages of advice for Games Masters looking to make their campaign’s encounters more enjoyable, more believable and more exciting.
Featuring pre-written scenarios that focus on a variety of monsters, some common and others remarkably under-utilised, that show them in two different lights, both as an encounter and at home in their lairs. These encounters can be placed in any appropriate setting and show the creature out of its typical habitat or roaming through a suitable type of terrain. Meanwhile, their lairs, though not always ones commonly associated with the creature in question, provide all the elements for adventure in and around it.
Encounter charts, broken up by terrain types and Challenge Ratings, allow a Games Master to select an interesting and challenging encounter for any level of play. Each table entry provides, a basic idea of how to scale creatures or Non-Player Characters to an appropriate difficulty, taking the guesswork out of figuring out how many orcs, and at what level of experience, constitute a suitable challenge for their band of adventurers.
With a Help for Games Masters section specifically dealing with how to run better encounters, design logical - though not stereotypical - lairs and plan out the ecology of different areas in a campaign world, linking seemingly unrelated scenarios into a coherent campaign plot line.
With The Book of Encounters & Lairs at his side a Games Master could run an entire campaign and never need another source of scenarios!"