by Mike Shea on 12 September 2016
Note: This article is a rewrite of the original from March 2015. Wizards of the Coast has released new encounter building tables in Xanathar's Guide to Everything which gives us a new way to build encounters on top of the rules in the Dungeon Master's Guide. Consider these guidelines another alternative for fast, simple, and loose encounter building.
The following guidelines aim to help dungeon masters running the 5th edition of Dungeons & Dragons build combat encounters quickly and easily. This article begins with a set of quick encounter building guidelines and then get into the design considerations later in this article.
These guidelines are intended to help DMs quickly build encounters and have a rough estimate of whether an encounter is deadly or not. These guidelines, like the underlying challenge rating of monsters, is not an exact science and will not build perfectly balanced encounters. Nor will any other system. Instead, it gives us easy-to-remember guidelines for building fun and interesting encounters that fit the stor taking place at the table.
The following is a more detailed look at the guidelines above. Note, these are intended to help you understand what a "hard" encounter looks like so you have the freedom to tune the battle to make it easier or harder depending on the story and your goals for the encounter.
1. Choose monsters based on the story. What monsters make sense for the current situation and direction of this story? You might know this ahead of time or might want to improvise a quick encounter right at the table. When designing an encounter, start with the story first and the mechanics second. When in doubt, read the Monster Manual to get an idea what makes sense for the monster. Use the monsters by challenge rating index or the excellent Monsters by Environment list in appendix B of the Dungeon Master's Guide to help you pick the right monsters for the situation.
2. If needed, determine if the encounter is deadly. Use some simple comparisons of monster challenge ratings and character levels to see if the encounter is likely to be deadly or not. If the encounter you designed goes above these baselines, it's potentially deadly.
For Levels 1 to 4
If a monster's challenge rating is roughly equal to the character's level, it is the equivalant of four characters.
If a monsters' challenge rating is roughly equal to 1/2 the characters' level, the monster is the equivalant of two characters.
If the monsters' challenge rating is roughly equal to 1/4 of the characters' level, the monster is roughly equivalant to a single character.
If the monsters' challenge rating is roughly equal to 1/10th of the characters' level, two monsters are the equivalant of a single character.
For Levels 5 and Above
If a monster's challenge rating is roughly three higher than the character's level, it is the equivalant of four characters.
If a monsters' challenge rating is roughly equal to 3/4 the characters' level, the monster is the equivalant of two characters.
If the monsters' challenge rating is roughly equal to 1/2 of the characters' level, the monster is roughly equivalant to a single character.
If the monsters' challenge rating is roughly equal to 1/4th of the characters' level, two monsters are the equivalant of a single character.
If the monsters' challenge rating is roughly 1/10th of the characters' level, four monsters are the equivalant of a single character.
Here's a quick lookup table with a more accurate comparison than the guidelines above that compares monster challenge ratings with character levels. Note that this table follows the encounter guidance in the Dungeon Master's Guide.
|Character level||CR for two monsters per character||CR for one monster per character||CR for one monster per two characters||CR for one monster per four characters|
3. Adjust difficulty if needed. During the battle we can adjust the difficulty on the fly by increasing or decreasing the number of monsters as some flee or new monsters show up, increasing or decreasing hit points within the monsters' hit dice range, or increasing or decreasing the monsters' damage.
The rest of this article discusses the design philosophy behind these guidelines. You need not read further unless you wish to understand how and why these guidelines were put in place.
The guidelines above let you mix and match a bunch of different monsters in a single battle by matching monsters with different challenge ratings with the level of the characters. For example, if you have a group of five level 7 characters, you can build an encounter with one challenge 5 troll (the equivalant of two level 7 characters), two challenge 2 ogres (the equivalant of two additional level 7 characters) and two challenge 1 bugbears (the equivalant of the one remaining level 7 character).
The math isn't perfect since 1/3 of level 7 and 1/4 of level 7 both round out to challenge 2. Theoretically you could have five ogres and a troll instead of two ogres, a troll, and two bugbears. That's certainly a harder battle but it still falls within the guidelines.
The challenge of any encounter in fith edition Dungeons & Dragons cannot be easily measured or quantified. There are too many variables to know how any battle is really going to go. Some of these include variance between monsters at the same challenge rating, the class mixture of characters, the particular spells a character group has access to, who wins initiative, circumstantial or environmental considerations, and the skills and proficiency of the players. The Dungeon Bastard reminds us that whether a group is fully rested or worn down will have a huge effect on how easily they can overcome the next battle.
Thus, all systems to determine the difficulty of an encounter in 5e will lack precision.
Due to the complexity of the encounter building rules in the D&D 5e Dungeon Master's Guide and the lack of precision in any encounter building system, we aim for a faster system that gives dungeon masters loose guidelines to balance encounters while acknowledging that the actual difficulty will still vary.
The encounter building tables in the Dungeon Master's Guide or the DM Basic Rules offer four levels of difficulty: easy, medium, hard, and deadly. As a rule of thumb, however, we really only need to worry about the "hard" battle. If we use fewer or lower challenge monsters than the "hard" budget allows, the battle is easier. If we use more or bigger monsters, the battle will be harder. This gives us a single baseline we can use to balance each encounter instead of worrying where it fits within a range of four imprecise difficulties.
We calculated these guidelines using the traditional encounter building rules aimed at a "hard" encounter and using the multiplier for the number of monsters assuming that the number of monsters will be roughly comparable to the number of characters. We make the assumption that most battles will have a roughly equal number of monsters to characters. Adjusting the difficulty from this baseline is easily done by removing monsters, choosing lower challenge monsters, or increasing or decreasing hit points.
We intend for these encounter building guidelines to be easy enough to keep in our head and usable right at the table when we want to build an encounter right now. We intend for these rules to aid in improvisational DMing with very little, if any, preparation required before the game is run.
There's a good reason the Dungeon Master's Guide has two tables we must cross reference to put together an encounter. Regardless of the individual power of a monster, the difficulty goes up every time we add another combatant to the battle field. Regardless of how hard they swing a sword, two knights get twice as many actions as one.
We call this the action economy. The more total actions on one side of a battle, the stronger that side is. The multiplier in the standard encounter building guidelines intends to account for this. If there are three to six monsters, they are significantly more effective than if there is only one. Thus we have a 2x multiplier on their experience point budget when we include them into an encounter. This increase in the action economy is why the rules for encounter building are so complicated. As Benjamin Reinheart often points out, the overall threat in combat increases at a geometric rate as you add more combatants to a fight.
For this reason, you likely want to have no fewer than one monster for the first four characters plus one additional monster for each character above four. Even an ancient red dragon is going to have trouble handling six high level characters and all of the things they can do in a round.
The intent of these guidelines isn't to ensure that every encounter our characters face is balanced. There should be many times our characters face small groups of easily defeated monsters and a few occasions where they might run into a foe they simply cannot defeat with straight-on combat. Instead, these guidelines are intended to give us a gauge to help us understand how any given battle might go. If we're way above the baseline, we know things are going to be rough and can help our players see that. If we're going way below, we know it will probably be an easy fight. Varying difficulty is a good way to ensure the story and the game feel fresh.
As we begin to understand our group's actual power, we can alter these guidelines to face them and D&D 5e's speed of combat makes it easy to do so. If a group of experienced players is running a strong group of well-coordinated and well-built characters, we can increase the challenge dramatically by increasing the challenge rating of the monsters we choose, increasing the number of monsters in the battle, increasing the hit points of those monsters, or increasing their damage. We can also go in the opposite direction with groups who aren't as experienced or well-coordinated. Fewer monsters, monsters of a lower challenge rating, or both will make battles easier for less optimized groups of players.
Again, these are loose guidelines meant to give us a starting point. As DMs, we are free to tweak these guidelines depending on our goals and the actual results we see at the table.
As Chris Sims stated above, the higher level the characters, the more the standard encounter building rules break down. Strong groups of characters played by experienced players can fight deadly battles far outside of the baseline for a "hard" encounter and still win. Other less experienced groups will have a harder time with such battles.
As DMs, we can start by using these guidelines and then tweak them as we need once we know more about the actual strength of our groups.
We built these encounter building guidelines to make your life easier when putting together a battle. Keep the numbers above in your head so you can quickly build a roughly balanced encounter for a challenging fight. Tweak to suit these guidelines to match the skills of your players and the power of your characters and focus your attention on the grand story of the game you share together.
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