This unique shield is a Shield of the Lightwatcher found and modified by the cleric Gideon Huxley in 3E482.
He had it combined with a Spellguard Shield, mixing together both the enchantments and changing the color of the shield.
shield, +2 AC, very rare (requires attunement)
The designs on this metal shield are ancient runes of light. The bracer has the Omnikarn word 'Liikranhl' itched on it, which means Lightwatcher.
While holding this shield, you benefit from the following properties.
Abysslighter. You have resistance to necrotic and radiant damage.
Cleansing Light. As an action, you can cause the shield to flare with the cleansing light of purity. Choose one creature you can see within 30 feet of yourself (you can choose yourself). One disease or condition of your choice affecting this creature ends immediately; the condition can be blinded, charmed, deafened, or poisoned.
Shield Bash. When a foe hits you with a melee attack, you can use your reaction to bash them with the shield. The creature must make a Dexterity Saving Throw, taking 3d6 bludgeoning damage and getting knocked prone on a failure.
Spellguard. While holding this shield, you have advantage on saving throws against spells and other magical effects, and spell attacks have disadvantage against you.