Elfshot

An invisible shard of necrotic energy shoots from your hand at a target within range. On a hit the target takes 2d8 necrotic damage, as their veins blacken and shooting pains wrack their body. The target must make a Constitution saving throw, on a success they take half damage and cannot take damage from another casting of Elfshot. On a failure they take full damage and for 10 rounds on each of their successive turns they must make an additional Constitution saving throw or take 1d4 necrotic damage as their life force slowly drains away. If you cast this spell at 3rd level or higher the damage die increases for 1d8 for each spell level above 3rd.