Sentinel

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 must make a Dexterity check with a DC equal to your attack roll. If the target fails this check, its speed becomes 0 for the rest of the turn.
• Creatures within 5 feet of you 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.