Relentless Avenger is an Oath of Vengeance Paladin passive feature. This ability allows a Paladin to pursue fleeing enemies.
Description
If you hit an enemy with an Opportunity Attack, your movement speed increases by 4.5m / 15ft on your next turn.
Condition: Relentless Avenger
Duration: 1 turn 
4.5 m / 15 ft bonus to your How to learn
Classes:
- Class level 7: Oath of Vengeance Paladin