OKay you’re new to D&D.
You’re new to being a Game Master.
You’ve read the rules to Challenge Ratings (CR) and you have questions about how to use the Challenge Rating system but don’t worry. Everyone did.
Let’s get you up to speed on how to begin using this.
First lets start with some basic math Ugh! Math! I know. But shut up. We’re not talking about algebra here. This is basic simple math that you use a calculator. Relax.
So the CR rating assumes that you have a party of four players.
STOP! Unpack that. Simply put, take the level of each player character and divide it by four. Don’t round up. Don’t round down. Don’t round ANYTHING.
Next step is to add up the totals. THAT’s the maximum CR rating for the monsters that you can throw at the PC’s. (Someone out in the ‘verse just screamed “yeah but!” Stop! Let me finish . . . I’ll get there).
Okay new GM. Let’s break this down with an example. Lets say that you have seven eager, bright eyed players ready to sit at your table! All of the player characters are first level so seven divided by four is 1.75. That’s your maximum CR rating that you can throw at your newbs. (Again, Someone just screamed “yeah but!” Again. Please. Let me finish . . .)
Now crack open your Monster Manual and go looking for some bad guys to have the Player Character’s beat up.
Oooo! Aarakocra have a CR of 1/4 (aka .25). That means that your 7 players can beat up 7 Aarakocra! Yay! Mission accomplished! Now it’s time to put together a scenario involving Seven aggressive Aarakocra.
Or you can check out the Aboleth. That has a Challenge Rating of 10. That creature will kill your seven players! You are a jerk as a GM if you throw an Aboleth against first level players. Total Party Kill! (TPK).
Okay that’s it. At it’s simplest; take the players level. Divide by four and THAT’s exactly how much CR in monsters THAT Player Character can kill. Total up their total party CR and that makes a good target.
Now to the “Yeah Buts!” that are bound to be out there.
Okay some dork player is going to want to play a Ranger and that’s going to throw off your math because Rangers suck. Warn that player that his character is going to die.
Your player isn’t convinced? Well, you warned them. Didn’t you.
When that character dies, just have that player roll up a new character. No, not another Ranger.
Congratulations! The Player Characters have leveled up a bit.
And now it’s time to let you in on a tiny little secret. The CR system for D&D 5E is completely broken. It’s not quite meaningless, but it’s ambiguous enough that as you gain experience with D&D that you’ll realize sooner or later that CR is really hard to gauge. That and each Player Character is somewhat customizable. Some players will be eager to Min/Max their players into the most efficient lethal death dealing dice dealer on the seven planes of existence while other players will focus more on the character back story with combat being a distraction.
But not to worry. As you get more experience seeing what kind of damage that your PC’s can deal, you’ll get to experiment with throwing more CR at the PC’s. Take notes and see what the PC’s are capable of beating and what gives them trouble.
Slowly increase the CR of monsters that you put up against the Player Characters.
In time, you’ll find that a good team of well experienced PC’s can easily beat up 2 – 3 times the CR rating of their current level. Especially if the PC’s are spell casters. One word: “FIRE BALL!”
Unless that Player Character is a Ranger. But how did that Ranger survive this long? If they did, then YOU as the Game Master have done something wrong. Repent and smite that Ranger more!
The other thing to remember is that first level Player Characters are as fragile as glass menagerie in a meat grinder. So the CR system is geared for making sure that you don’t TPK a group during the first session.
As unlikely a scenarios this is, I can see it happening. Once.
First, take ownership as a Game Master that you did something wrong.
You didn’t focus fire on the Ranger.
Also, make sure the monsters loot the dead PC’s stuff, so that the Ranger can’t walk home with any loot. And definitely not the bard’s lute.
And that Ranger doesn’t get any XP for fleeing. Nope! We can’t have you rewarding bad behavior.
You should also ambush the Ranger on the way home with that Aboleth.
Just be prepared to explain to your players that any other group of Player Character Classes could have easily bested that number of Aarakocra. The rules say so.
D&D 5E combat is really a balance of odds results. With the dice results being equal the CR system should get you results where the PC’s win the encounter. If you throw too many opponents at the Party, then Player Characters start dying.
Yeah occasionally the GM’s dice are hot and the PC’s are not. But character death should (in 5E) be pretty rare. As a player it’s not a lot of fun dealing with making a new character when everyone else gets to level up.
In short this is starter advice for starter DM’s new to the system. As you gain more experience as a Game Master, then you’ll see how you can tweak the encounters to make them more challenging for the party, without inflicting a Total Party Kill.
There are also a lot of other Game Master’s out there ready to teach you how to manage encounters, once you get some gaming under your belt and you are comfortable with the basics of this system.