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.