Rapid Strike

Praetorian Specialist: 15th level You learn to trade accuracy for swift strikes. If you take the Attack action on your turn and have advantage on an attack roll against one of the targets, you can forgo the advantage for that roll to make an additional weapon attack against that target, as part of the same action. You can do so no more than once per turn.

Granted by Praetorian Specialist at 15th level.