As per this dnd 5e feat you have become mastered techniques in taking advantage of every drop within any enemy’s guard, you can also gain the below mentioned advantages.
- Whenever you had hit the creature by using an opportunity attack, it’s speed has been dropped to 0 for the sake of rest of a turn. This will stop any kind of movement they may be taking.
- Some of the creatures are almost within your reach provoke an opportunity could attack even if they would have taken Disengage action.
- Whenever the creature within your reach can make an attack against the target but other than you (and even that target doesn’t have this feat), you can also use all of your reaction for being make it a melee weapon attack against to the attacking creature.