charged shadow shoot

you arm at a creature with the ranged weapon you use and you create a shadow arrow. the arrow is soonly starts to have some little dark spark like thing around it like an aura(or idk).then you shoot at the target. the target needs to take a dexterity saving throw. if it succes it can dodge it. but if it fails on the throw it takes 3d12 necrotic damage.

if you miss with the shoot somehow, you take 1d6 necrotic damage.

only can be used once per long rest.