Armor of the Void (5e Equipment)
From D&D Wiki
Armor (any), legendary (requires attunement)
Nearly a solid, deep black material, the Armor of the Void is, somehow, constructed almost entirely out of it's namesake. While it takes the simple shape of armor, the sheer aura emanated by it is frightening, and enough to strike the fear of god in the hearts of those who can see that presence. It shares some of it's home planes abilities, swallowing some attacks against it's wearer whole.
When you are targeted by something that would damage you, for the next minute, your AC and bonus to Constitution saving throws increases by +1, to a maximum of +4.