Encounter Building
This section introduces new guidelines on building combat encounters for an adventure. They are
an alternative to the rules in “Creating Encounters” in chapter 3 of the Dungeon Master’s Guide.
This approach uses the same math that underlies the rules presented in that book, but it makes a
few adjustments to the way that math is presented to produce a more flexible system.
This encounter-building system assumes that, as DM, you want to have a clear understanding of
the threat posed by a group of monsters. It will be useful to you if you want to emphasize combat
in your adventure, if you want to ensure that a foe isn’t too deadly for a group of characters, and
if you want to understand the relationship between a character’s level and a monster’s challenge
rating.
Building an encounter using these guidelines follows a series of steps.
Step 1: Assess the Characters
To build an encounter using this system, first take stock of the player characters. This system
uses the characters’ levels to determine the numbers and challenge ratings of creatures you can
pit them against without making a fight too hard or too easy. Even though character level is
important, you should also take note of each character’s hit point maximum and saving throw
modifiers, as well as how much damage the mightiest characters can deal with a single attack.
Character level and challenge rating are good for defining the difficulty of an encounter, but they
don’t tell the whole story. You’ll make use of these additional character statistics when you
select monsters for an encounter in step 4.
Step 2: Choose Encounter Size
Determine whether you want to create a battle that pits one creature against the characters, or if
you want to use multiple monsters. If the fight is against a single opponent, your best candidate
for that foe is one of the game’s legendary creatures, which are designed to fill this need. If the
battle involves multiple monsters, decide roughly how many creatures you want to use before
continuing with step 3.
Step 3: Determine Numbers and Challenge Ratings
The process for building fights that feature only one legendary monster is simple. The Solo
Monster Challenge Rating table shows you which challenge rating (CR) to use for a legendary
creature opposing a party of four to six characters, creating a satisfying but difficult battle. For
example, for a party of five 9th-level characters, a CR 12 legendary creature makes an optimal
encounter.