The Challenge Rating (CR) system in Dungeons and Dragons is essentially like levels in a video game. A CR 2 encounter is meant to be “of medium difficulty” for a party of level 2 adventurers.
Nine times out of ten the party will be able to walk away from an encounter of that challenge rating with no casualties beyond expended resources.
A party can usually handle around six to eight encounters with the same challenge rating as themselves within a day.
Assuming the party is able to take a couple of short rests of course!
This system means the encounters feel easier earlier in the day when the party have all their resources.
Come evening the same level encounter can feel quite challenging with characters running low on spell slots or hit points.
It's worth noting that the Challenge Rating works off the presumption that you are creating an encounter for a party of four adventurers and requires some tuning for parties of different sizes.
How monsters are given a rating
A few things get considered when giving monsters a challenge rating. They tend to come under one of the following four headings; their hit points, damage output, armor class and special abilities.
If you want to assign a challenge rating to a monster you create yourself, start by comparing your creature to existing monsters with similar abilities and characteristics.
Adapting a balanced stat block is a lot easier than starting from the beginning!
If you’re starting from scratch, check out monsters of your desired CR level and use them as a reference point.
Consider their hit points, attack bonuses, damage output, and defences, paying special attention to the creatures special abilities.
This will give you a sense of where your monster falls on the challenge scale.
Limits of the CR system
The Challenge Ratings are more guidelines than rules themselves. They give an indication of how powerful your encounter is but they should not be relied on to be completely accurate.
It’s an easy to assume that the CR system will be safe to rely on when creating encounters but doing so can lead to premature TPKs.
The D&D CR system has a lot of limitations and can get pretty broken at times. If we stop and think about it that’s not really surprising though.
Encounter difficulties vary a huge amount depending on party composition.
A creature with wings and a ranged attack is going to have a much easier time fighting a party of melee fighters than spell slingers.
Here’s a few other things that CR can’t take into account:
In my opinion, without any of this information, the Challenge Rating can only ever be treated as guidelines. It will need you, the DM, to check the encounter and ensure it seems achievable for your party.
It’s also worth mentioning that as a separate problem, some monsters are wildly mislabeled.
Shadows have a challenge rating of 1/2 but could cut through a level 1 party like butter.
Monsters like these are why it’s always worth weighing the encounter yourself to see if it feels balanced, rather than just relying on the challenge rating.
Ok, it might sound like I’ve been bashing the Challenge Rating system a lot but I think it’s good practice for Dungeon Masters to evaluate the tools they have at their disposal and to understand their limitations.
Once you understand the flaws of the CR system it does become a really useful tool for Dungeon Masters when crafting encounters. Which leads me onto the next bit …
How to practically use Challenge Ratings
If you want to use challenge ratings to help build encounters then go for it. It can be really helpful - I use it myself!
Just remember that the CR system tells you “If you add up each monsters individual CR in an encounter and it equals the average level of a party of four adventurers and they are having about 6-8 of these encounters in a day with a couple of short rests … then your party should find it medium difficulty”
The Challenge Rating system works best when your encounter is made up of a mix of multiple creatures (rather than being on either end of the Mobs Vs Solo Villain scale).
This is because having multiple creatures means multiple actions occurring in a round, providing more balance against a party of adventurers.
I like to use CR as a way to check if I’m around the right ball park when creating an encounter.
If I’m just throwing something together I’ll probably use the D&D Beyond encounter builder (not sponsored, it’s just the one I personally use), add what monsters I think make sense and keep an eye on how challenging the encounter is calculated as.
I usually want it to warn me the encounter is deadly (but not too deadly!) - that’s because I often run less combat encounters in a day and want the fights we do have to feel more epic.
Once I’ve got to that point I’ll think about my party and their abilities, compare them to the monsters abilities, consider the likely terrain for the combat and decide for myself if anything needs adjusting.
By the way, don’t be shy of throwing extra challenges from the environment in there to make things fun!
If the villain is in their lair, give them a trap to lure players into. If we’re in a monsters natural environment then think about how they use features of the terrain to their advantage!
This helps your monsters feel more realistic and makes encounters more challenging for the players.
So! We’ve learned what Challenge Rating is, how it’s calculated and what it’s limitations are. We also learned how best to use the CR system with strategies like designing encounters to have a mixture of different foes to minimise the unreliability.
You should be well equipped to go forth and create your own encounters using the D&D Challenge Rating System.
As some final parting advice…
I suggest you use the CR system when building a D&D encounters, but rely on yourself to check it over. Think about your party and their abilities, and at the end of the day, if it ends up being a big strong they can always run away!
Hi! I'm Annabelle! I'm the author of this blog and a huge nerd!
I also make magnetic, double-sided, modular dungeon tiles!
My DnD terrain contains secret spinning magnets so that each piece snaps instantly to every other. They even come in a box disguised as a spellbook to store away on your bookshelf!
They're really cool, you should totally check them out here!