You can use this feature if you need to make a custom state or behavior and call it at any time.
To make a custom behavior first you need to create a new blueprint class:

Then choose “MonsterCustomBehavior”

After you open the behavior graph you can use “Event Behavior Start” and “End Behavior” to add your logic between them:

Here is an example of a stun behavior:

Also you can get the monster reference and call any event from the “Monster_NPC” class so you can play animation or play a sound:


After you finish building your behavior you can call this behavior from anywhere inside the monster class by calling “Run Custom Behavior” and choose the behavior you created:

Note: as you noticed in the behavior graph you can choose a specific behavior in “End Behavior” that monster will go to after finishing the behavior:
