Blackfire Bolt

You launch a mote of black fire at a creature or object within range. The target must make a Dexterity saving throw. On a failed save, a creature takes 1d4 Fire damage and 1d4 Necrotic damage and cannot have its Hit Points restored until the end of its next turn. On a successful save, it takes half as much damage but still suffers the additional effects. Constructs automatically succeed and take no additional effects.

Cantrip Upgrade. The damages increase by 1d4 when you reach 5th level (2d4), 11th level (3d4), and 17th level (4d4).