Boon of Peerless Parrying (5e Epic Boon)
From D&D Wiki
Boon of Peerless Parrying
While wielding two light weapons, your martial skills help you defend yourself, and gain the AC benefit of wielding a shield (+2). You may set yourself into a defensive stance as a bonus action, and if you do so, you may "Parry" any attack until your next rounds. While parrying, you may add your Dexterity modifier to your armor class against an attack made against you.