Enfeebling Arrow

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. An affected creature can make another saving throw at the end of its turn to attempt to end the effect. 

When you cast this spell using a spell slot of 2nd level or higher, the necrotic damage increases by 1d6.