Editing Unwritten: System Reference Document/Stunts and Resources (section)

==Balancing Stunt Utility==

If you look at most of the example stunts, you’ll notice that the circumstances under which you can use them are pretty narrow compared to the base skills. That’s the sweet spot you want to shoot for with your own stunts—you want them to be limited enough in scope that it feels special when you use them, but not so narrow that you never see them come up after you take them.

If the stunt effectively takes over all of the skill’s base actions, it’s not limited enough. You don’t want a stunt replacing the skill it modifies.

The two main ways to limit a stunt are by keeping its effects to a specific action or pair of actions (only creating an advantage or only Oppose rolls), or by limiting the situations in which you can use it.

For the best results, use both—have the stunt restricted to a specific action, which can only be used in a specific in-game situation. If you’re worried about the situation being too narrow, back up and think of the ways the skill might be used in play. If you can see the stunt being relevant to one of those uses, you’re probably on the right track. If you can’t, you may need to adjust the stunt a little to make sure it’ll come up.

You can also restrict a stunt by only allowing it to be used once in a certain period of game time, such as once per conflict, once per scene, or once per session.