Once per encounter?

You may use the ability one time during a single scene of active danger or direct conflict. An encounter begins the moment the character enters a situation where actions matter in a focused, moment-to-moment way - such as fighting, chasing, negotiating under threat, or dealing with an immediate hazard.

The encounter ends when the danger has passed, the opposition is no longer acting against you, or the scene naturally shifts out of urgent action. When the tension drops and characters are no longer making quick, decisive moves, the encounter is over.

After it ends, the ability refreshes and can be used in the next dangerous scene. Dungeon Narrator will decide when an encounter ends so your ability refreshes. Any questions, ask your DN.