Source: Explorer's Guide to Wildemount

Armor (leather), very rare (requires attunement)

You gain a +1 bonus to AC while wearing this armor.

The coat has 3 charges. When you hit a creature with an attack and that creature doesn't have all its hit points, you can expend 1 charge to deal an extra 1d10 necrotic damage to the target. The coat regains 1d3 expended charges daily at dawn.