Much more than a collection of monsters, this book is the essential tool for spawning your own creatures, traits, and lifepaths. Inside the Monster Burner are the detailed guidelines you need to understand and manipulate the Burning Wheel character burning system.
Obviously, this is an older version of The Burning Wheel, and so much of this content I had already read in a more polished form (The Burning Wheel Codex), but this book also pulls back the curtain on so many of the fundamentals of the game that it was invaluable for me in understanding how to use the ttrpg to its greatest potential. Highly recommended.
Damned good supplement for designing your own monsters, not even just for Burning Wheel. I mean sure, it'll work the best if you use the system as well, but there's plenty of background notes and good questions and design suggestions to work anywhere.