When you run NPCs as the GM, you should always strive to follow your GM principles and use them to bring the world to life. Differentiate each character by the unique ways they speak and act—you can use a new voice, posture, or set of mannerisms if you’re comfortable—and lean into their individual motives to fill the world with dynamic, active NPCs.

Choosing NPC Statistics

Many NPCs don’t need page-long backstories or their own stat block—if the PCs are simply interacting with a friendly bar patron to gather information, you probably just need a name, description, and motive. These three things give the NPC a moniker, a way to recognize them, and a purpose behind their actions. If they’re someone the PCs might try to make a roll against, consider also giving them a Difficulty. You can use the examples in the earlier “Setting Roll Difficulty” section or base it on similar NPCs you’ve already introduced.

If you’re improvising a creature who isn’t interacting with the party socially, it’s still important to think about motive, but you’ll want to focus more on the information needed to play them in battle. You can grab an adversary stat block of a similar creature and make some changes—or if you prefer, improvise your own using the guidance in the “Improvising Adversaries” section of chapter 4, then decide their features when you have the chance to make a GM move. That allows you to choose something that will have the most interesting impact on the scene at that moment.

Using NPC Allies

NPCs can also become allies in a fight. If this happens, you don’t need a stat block for them—instead, put the spotlight on them and what they do, showing how the fiction changes because they’re involved. When they act to help the PCs, and if a PC capitalizes on that help during their next action, give the PC advantage on the roll.

Even if an NPC doesn’t have Hit Points or Stress, they aren’t immune to danger and tragedy—they can get seriously injured or even die as a result of the narrative. During your GM move, don’t be afraid to capture and threaten the NPC to drive the PCs to action, trap the NPC and force the PCs to make a difficult choice, or push on the NPC’s motive so hard that they do something that endangers everyone. When it’s justified, hit the NPC hard. Allow them to be beaten and broken after a difficult fight, or have them die in the party’s arms if the narrative says they should. You run both the adversaries and NPCs—you control their story and fate. Follow the fiction, embrace your GM principles, and make moves that drive interesting conflict for the party.

NPC Features

If you want an important NPC to mechanically interact with the system, you can give them one or more features that reflect how they move through the world. At your discretion, you can share these NPC features openly with your table, allowing players to help keep track of them, or keep them private, so an NPC’s actions feel more organic and narrative-focused.

An NPC feature works similarly to an adversary’s reaction, but it is broken down into the trigger and the effect. The trigger is the event that makes the NPC behave in a certain way, and the effect is what mechanically occurs because of that trigger. For example:

Not On My Watch

Trigger: A PC within Very Close range marks at least 2 Hit Points.

Effect: Roll 1d8. On a 4 or higher, this NPC moves into Melee range of the PC and marks one of the Hit Points instead. Reduce the die size by 1 (from 1d8 to 1d6, then 1d6 to 1d4). Once you must reduce the die below 1d4, this feature can’t be used again until this NPC finishes a long rest.

In this example, any PCs within the NPC’s Very Close range have a chance of taking less damage because of the ally, but if they do, the odds of that NPC being able to reduce damage again decrease. Once the NPC can no longer trigger the effect, they can’t use that feature until they rest and recover.

These triggers and effects are designed so you can include other mechanics alongside them—such as countdowns, rolling dice, and dealing damage—to represent an NPC’s complex and dynamic interactions with the world. On the flip side, you can also tailor these elements to be as narrative-forward as needed for your playstyle and table.

Optionally, an NPC might also have a choice. The choice represents a specific parameter by which the trigger and effect will operate. For example:

Arcane Hold

Choice: When the battle begins, choose a favored PC.

Trigger: The first time during a battle the favored PC is within Close range and hit with an attack.

Effect: Make an attack roll with a +6 modifier against the adversary. On a success, the target is temporarily Restrained by tendrils of powerful magic.