You launch a single drop of blood infused with dark energy at a creature you can see within 60 ft. Make a ranged spell attack against the target. On a hit, the bolt deals 1d8 necrotic damage. The target must then make a Constitution saving throw. On a failed save, it is Weakened until the end of its next turn.   A Weakened creature has disadvantage on Strength-based ability checks and saving throws, and its Strength-based melee attacks deal half damage. Creatures that are immune to poison or exhaustion are immune to the Weakened condition.