Sentinel

You have mastered techniques to take advantage
of every drop in any enemy's guard, gaining the following benefits:
•Hitting a creature with opportunity attacks,
drops their speed to zero for the rest of the turn.
•Creatures within reach provoke opportunity
attacks even if they took the Disengage action.
•If a creature within reach attacks a target other
than you (and that target doesn't have this feat),
you may use a reaction, make a melee weapon
attack against that creature