Hell Forged Armor (5e Equipment)
From D&D Wiki
Armor (plate), legendary (requires attunement)
A red armor that, when attuned, is constantly on fire, the fire reflects the emotion and condition of the wearer, if the user is unconscious the fire will cease, if they are extremely angry the fire will flare up. When wearing this armor your melee attacks do an additional 1d4 fire damage. If you are attacked the attacker takes 1d6 fire damage. This armor grants +2 AC.
When wearing this armor any fire attacks you make deal an additional 1d6 fire damage. While wearing the armor you are immune to fire damage and resistant to dragon fire.