by Mike Shea on 26 February 2018
On an episode of Dragon Talk, D&D developer and rules sage, Jeremy Crawford, spent a good deal of time digging deep into encounter building, particularly into building combat encounters. It's a wonderful episode and one I highly recommend listening to.
Since the release of the fifth edition of Dungeons & Dragons, I've had two obsessions: narrative combat and D&D 5e encounter building guidelines. The official approach to D&D combat encounter building has changed since its release, most recently with the release of the combat encounter charts in Xanathar's Guide to Everything. Some of the developers of D&D themselves, like Mike Mearls, [don't use any sort of mathematics to balance encounters at all], instead choosing to build encounters that make sense for the story.
During this episode, Jeremy Crawford shined a lot of light onto what Wizards of the Coast expected when it came to D&D combat encounter building. This article summarizes much of what he said in the interview so we have some textual representation of this outstanding discussion.
Let the summary begin...
Encounter building is more than just worrying about challenge rating.
The guidelines in the Dungeon Master's Guide are intended to help DMs recognize how difficult an encounter might be. The math of encounter building is all about determining whether combat will be deadly or not.
From a common vocabulary standpoint, the term "encounter" doesn't just mean combat encounters. Encounters can represent represent any type of scene. Combat encounters are a subset of all encounters.
There is no one right way to build an encounter. There's no perfect formula. The drunk goblin at the gate could be more fun than a well calibrated set-piece battle.
Going through the math of determining encounter balance is really just there to help us answer the question "is this going to kill them all?"
The encounter building rules can also tell you if it's going to be too easy, just right, hard, or super hard.
The DMG encounter rules just give you a sense of how a battle might go. So many variables can change the difficulty of an encounter. Four ogres on a road is a very different challenge than four ogres on a rope bridge over lava.
The dice also have a big effect on the difficulty of an encounter. The recharge of a dragon's breath might be the difference between victory and death. Players who roll well can also make a hard battle easy.
The variability of encounters is a design, not a flaw. Not even the DM should be able to fully predict how a battle goes. This uncertainty is the game from the DM's side. This is what makes the D&D a fun game for the DM as well. DMs aren't puppet masters who control everything, they too can be surprised.
Jeremy rolls recharge dice in the open, sometimes letting the players roll for a dragon's breath recharge.
Opportunities to improvise lead to a DM's fun.
Catastrophe can lead to really fun problems. Lean in to failure.
A monster's challenge rating communicates that the monster will probably not wipe out three to six characters of a level equal to the monster's challenge rating. A CR 3 monster will not likely wipe out three to six characters of level 3.
This gets tricker with multiple monsters. Legendary monsters are intended to run on their own, other monsters are not.
Jeremy built a spreadsheet to handle the DMG's encounter building guidelines but suggests that the tables in Xanathar's Guide to Everything are a better choice.
A correct encounter is one in which the players had fun.
Wizards of the Coast used the encounter building guidelines in Tomb of Annihilation only to judge whether an encounter was harder than they wanted it to be. It wasn't a way to ensure that an encounter is an equal challenge to a specific level of characters. This is the way WOTC uses it and also how they suggest we DMs use it. Encounter building guidelines are intended to help us gauge whether an encounter is more deadly than we intend.
A DM could use Xanathar's Guide to adjust battles to fit characters of a specific level but this is not the expected design. The design of 5e is intended to be an open world where challenges are not designed to progress with the level of the characters. You might talk your way out of the problem or find some other way.
Jeremy rewards groups that subvert encounters as much as if they had defeated the monsters in an encounter.
Jeremy likes to put encounters in front of characters that are way more difficult just so the players see that the world is a living world not designed for them. It's a chance for the players to navigate a situation without combat. Quest giving NPCs will give clues to the difficulty. "Are you SURE you want to go in there?" An NPC can yell "fly, you fools!"
Jeremy likes to ramp encounters up. Monsters join in a battle partway through. There is a rising tension as more monsters show up. Sometimes allies show up and ramp the difficulty down. Jeremy likes to have friendly creatures show up in a battle.
Jeremy also likes to have timed elements. If all three gems light up, something awful happens.
Jeremy likes villains that introduce complications. He likes the classic villain who simply says too much. A villain might plant a seed of doubt in the characters during combat. Some villains are worse than others. A foe can put in a seed out doubt into whether they should be fighting at all. Strahd can be an ally!
Jeremy had a group of necromancers with a sign on their bodies. If they are killed, they return as some form of undead until the mark is destroyed. This is a fancy way to add more monsters to a battle. "More dudes show up" is the goal but we can wrap that in interesting story reasons.
Jeremy suggests we throw encounters at characters that are also easy so they can feel powerful as they progress.
Encounter guidelines that put the exact correct number and power of monsters will make the game boring. Perfectly crafted encounters can feel monotonous. Design easier and harder encounters and use the encounter guidelines in the DMG and Xanathar's to help you asses that potential difficulty.
Jeremy suggests we learn how to change difficulty on the fly. One of the easiest things DMs can do is change hit points within the range of the monsters' hit dice. Hit dice are a potential range of hit points. Raise hit points to make them tougher or lower them to make them more like 4e minions. According to Jeremy, modifying hit points within the hit dice range of a monster is fully within the rules of D&D 5e. We are using the monsters as intended when we play with the range of hit points. The listed hit points are the average for that type of monsters. We get to choose their range. It's not cheating.
During the battle, we DMs can shift hit points for narrative effect. If a powerful blow hits and it makes sense for the monster to fall, it can fall.
The DMG states six to eight encounters for a long rest. Some DMs say that this is the correct number of encounters. This is not how it is intended. If you're curious how much they can take in a day, six to eight is typical. WOTC does not suggest that this is the correct number. Like encounter building guidelines, its intended to help a DM gauge how hard the game will be if encounters go up to or beyond six to eight per day.
As the rules sage, Jeremy has answers to common rules questions over at the D&D website.