The Challenge Rating system in D&D 5e promises to be an easy way to make balanced, enjoyable monsters, encounters, and whole adventures, and is a foundational part of the game. Adventures, monsters, and treasures are all organized and understood by their CR. However, the vast majority of D&D players and dungeon masters find the way CR is presented unsatisfactory or downright confusing, so don't use CR to much effect.
Challenge Rating: Getting the Most out of CR for Improvisation and Monster Design is a re-worked presentation of the core D&D 5e CR. In it, I detail my approach to making CR work for me to quickly pull together improvisation-friendly adventures and encounters. I also show how to use the monster designing guidelines in the Dungeon Master's Guide the way you've always wanted to: pick a CR, slap on some special abilities, and have a fun and balanced new foe in a couple of minutes.
This isn't a variant CR system or a new way to make monsters work in D&D. All of the rules presented here are 100% core Dungeons and Dragons, but re-worked and presented in a way that makes them radically more straightforward and usable at your table. Chapter 1 shows you how to trust CR to abstract away the math behind a challenging encounter, so that you can focus on story and roleplaying when outlining an upcoming adventure. Chapter 2 shows you an efficient system to use CRs to prepare infinitely-reusable lists of monsters, letting you do all the math once for an encounter type you'll be able to use for parties of any size and level (some examples like "Necromancer Cabal" and "Bandit Camp" are provided). Chapter 3 re-works the monster design guidelines in the Dungeon Master's Guide so that you can start with a target CR and then quickly make a monster that fits.
My hope in writing this book is to empower you to understand and use the monster math in D&D to make your own adventure planning faster and more focused on the story, leaving questions of balance up to the system that is supposed to handle them.