You have mastered Techniques to take advantage of every drop in any enemy’s guard, gaining the following benefits:
When you hit a creature with an opportunity Attack, the creature’s speed becomes 0 for the rest of the turn.
Creatures provoke Opportunity Attacks from you even if they take the Disengage action before leaving your reach.
When a creature within 5 feet of you makes an Attack against a target other than you (and that target doesn’t have this feat), you can use your Reaction to make a melee weapon attack against the attacking creature.