Stunning Strike is a Monk feature gained at level 5 in the 2024 SRD. Once per turn when you hit a creature with a Monk weapon or an Unarmed Strike, you can expend 1 Focus Point to attempt a stunning strike.
Once per turn when you hit a creature with a Monk weapon or an Unarmed Strike, you can expend 1 Focus Point to attempt a stunning strike. The target must make a Constitution saving throw. On a failed save, the target has the Stunned condition until the start of your next turn. On a successful save, the target's Speed is halved until the start of your next turn, and the next attack roll made against the target before then has Advantage.