by Mike Shea on 7 August 2017
Choose the type and number of monsters appropriate for the story and situation.
Judge the relative difficulty of the encounter with our encounter building guidelines. As a loose rule of thumb a battle is considered "deadly" if, given an equal number of characters and monsters, the monster's CR is equal to half of the character's level. For example, a battle with five level 10 characters facing five CR 5 hill giants is considered just over the edge into "deadly".
Give the characters fair warning if they're taking on something too hard with a "you feel this challenge is beyond you" warning.
"I copy down a few stat blocks and make notes on what makes an area interesting. I don't use the encounter building rules. Fights are as tough as is appropriate to the location and situation."
When it comes to designing combat encounters, Wizards of the Coast describes two different ways to balance combat encounters in the fifth edition of Dungeons & Dragons. The first is the crazy two-dial system found in the Dungeon Master's Guide. For many DMs, these rules are too cumbersome to use and don't really balance encounters anyway even when you go through the trouble. The other official encounter balance rules come in an Unearthed Arcana on encounter building rules. These guidelines are much better, much easier to use, and accept the fact that, given the wide range of monster abilities within a given challenge rating, it's a loose guide at best.
There are other options as well. In the 2016 D&D Dungeon Master Survey, roughly 14% percent of respondents mentioned Kobold Fight Club as one of the top three best tools for running D&D games. It is a much easier way to use the calculations of the official rules to develop "balanced" encounters. We here at Sly Flourish wanted something a little simpler, something we could keep in our head. Thus we came up with our own encounter building guidelines as well.
There is another way we can build encounters, however. One that takes no math at all and is used by many DMs already, including Mike Mearls, the creative lead for Dungeons & Dragons. Here it is:
Choose monsters based on what makes sense for the scene and the story.
If the characters walk into the Glacial Rift of the Frost Giant Jarl, there will no doubt be a lot of frost giants there. They won't be conveniently split up into encounter-appropriate group sizes. If the characters kick open the doors during a frost giant feast, there will be a lot of frost giants in there. It doesn't matter if the characters are level 6 or level 16. We don't sit around with Kobold Fight Club and determine what the challenge level is. The giants are there because they should be there.
Let's look at another example. Maybe our level 8 characters are wandering through the streets of Hillsfar making sure that the recent political troubles haven't caused a crime wave. Sure enough, we see a band of ruffians breaking windows and ripping off fine dresses from Madame Yvoniva's Delights. If we're to use standard encounter building rules, we'd discover that we'll need some beefy NPCs to match up against a group of level 8 characters; swashbucklers, gladiators, master thiefs, and the like. But what the hell would gladiators, swashbucklers, and master thieves be doing running around the streets stealing dresses? How many swashbucklers and master thieves are there in Hillsfar? Wouldn't it be more likely to be a bunch of bandits?
Many times we DMs tend to build "appropriate" encounters without taking into consideration what is likely to be there. Bandits are likely. Gladiators and master thieves aren't likely.
There's nothing wrong with an encounter against a handful of bandits, even if they are way underpowered for the characters. It just makes sense that they'd be bandits. It also gives the characters a chance to shine against the typical riffraff of the seedy streets of Hillsfar.
If you're running a battle like this, you probably don't even need to break out the battle map and the miniatures. This is a fine time to consider running it using either a loose abstract map or the theater of the mind.
Sometimes, like in the example of the raid against the frost giants, things are way more dangerous than a gang of bandits. A party of level 6 characters is going to have a real hard time against twelve frost giants. In this circumstance, it behooves us DMs to give the characters fair warning. Sure, it might be obvious to you and, we can hope, to the players, but best to be sure. Players have a tendency to metagame things like this and might expect that we've somehow tuned the battle so they won't get wiped out. Of course, we have no intention of pulling punches if they do something stupid. Before they go kicking in the door, we might help them out a little bit by saying something like this:
"You believe this fight may be beyond you."
That's a powerful phrase using in-game language that gives the players fair warning that they might be facing a deadly encounter.
If you're running an entire campaign without generally tuning encounters around the level of the characters, you might want to say so right up front.
"The world does not conform to your level of power. Much will be less powerful than you, some will be more powerful than you. Heed this warning."
These warnings will help your players understand just how they will want to act in the world.
How do you know if an encounter is too hard and deserves this warning? We can use the basic formulas in our encounter building guidelines to gauge how hard a fight might be:
You can also simplify this further with the following rule of thumb:
Given an equal number of characters to monsters, a battle is considered deadly if the monster's CR is half of the character's level.
As we discuss in the encounter building guidelines, this can be affected by a whole lot of variables including how many battles the characters have faced previously, the circumstances of the battle, the delta in actions between characters in monsters, the synergy of the character classes, and the experience of the players. These are far from solid encounter balanced rules and much more loose rules of thumb to help us DMs understand what to expect when the characters kick in a door into a room full of frost giants.
Sometimes the story calls for a fight against large mobs of monsters. For example, our band of adventurers finally pisses Strahd off enough that he sends an army of one hundred zombies to attack them. How do we run that?
Page 250 of the Dungeon Master's Guide gives us a set of guidelines for running large amounts of monsters against a smaller group of characters.
We've also built a handy mob combat calculator to give us the flexibility to run battles with any number of monsters we wish just for situations like this. If you're running more than a dozen monsters, consider using it to help you quickly adjudicate hits per character and the like.
With these mob rules in our toolbox we can run battles with anywhere from one to a thousand monsters. We can run any number of monsters based on what the story calls for.
We DMs can make our lives unnecessarily hard. Figuring out what matters most to our games and eliminating what doesn't is the key to the way of the lazy dungeon master. Further, this elimination can actually make our games better at the same time.
Removing complicated encounter building rules and focusing on a single encounter building guideline of "choose monsters that make sense for the location and situation" is a perfect example of this simplification. It focuses our mind on the story and the situation instead of worrying about building perfectly balanced combat encounters. It builds dynamic play into the game by making scenes flexible depending on what happened before. It lets characters show off their powers against weaker foes and occasionally lets them get in over their heads and realize that the world does not conform to their level.
The next time you're sitting down to choose what monsters inhabit a location, skip the math and ask yourself, "what makes sense?".
If you enjoyed this article, take a look at Return of the Lazy Dungeon Master, Sly Flourish's Fantastic Adventures, and Sly Flourish's Fantastic Locations. You can also support this site by using these links to purchase the D&D Starter Set, Players Handbook, Monster Manual, or Dungeon Master's Guide.