When a friendly creature uses a maneuver you know within your reach, you can take a reaction to use the same maneuver without expending stamina points.
You and any wounded friendly creature that starts its turn within 10 feet of you regain a number of hit points equal to your AC. Moreover, while wounded, when a hostile creature within reach that you can see hits you or a friendly creature an attack, you can take a reaction to halve the damage.