Book of Hidden Paths, The

You get 10 main chapters, each devoted to a particular type of wilderness terrain: Caverns, Desert, Forest, Grasslands, Hills, Littoral, Mountains, Ocean, Tundra and Wetlands. After a brief discussion of that terrain type, each chapter launches into a series of tables and sub-tables outlining possible plausible encounters. They cover most of the creatures included in the Pathfinder Reference Document, from familiar wild animals to exotic monsters like kraken and purple worms, plus humanoids, various vocations/professions, and physical hazards that you can use for petty harassment (just to remind your players that adventuring isn't all fun and glory). In turn, each table entry discusses how that creature reacts - topics range from how to acquire a pet rat to what that ancient red dragon is thinking as it looks down at your party - how many of them are present (scaled to your party's average level), and what treasure might be gained from defeating it. Book of Hidden Paths gives DMs a deep dive into an under-explored aspect of RPGs. Even experienced DMs will find food for thought and fresh ideas about how to make a party food for monsters.