Enfeebling Arrow

Source: Xanathar’s Guide to Everything p. 29
You weave necromantic magic into your arrow. The creature hit by the arrow takes an extra 2d6 necrotic damage. The target must also succeed on a Constitution saving throw, or the damage dealt by its weapon attacks is halved until the start of your next turn.

The necrotic damage increases to 4d6 when you reach 18th level in this class.