The Book of Beasts is a bestiary you can play. Each beast comes ready to play with tailored random encounters, presenting the Gamemaster with a handy set of mini-adventures ready to go for Forbidden Lands. The book also includes legends about each monster, introduces the option to harvest resources from slain beasts, and lets the player characters use their Lore skills to gain insight into a monsters strengths and weaknesses. This will help them defeat or at least survive an encounter with the book's monstrosities.