Condemn

You extend a finger channeling further harmful energy into a creature. Make a ranged spell attack, on a hit the creature takes 1d6+spellcasting modifier necrotic damage. If the creature is under the effects of a spell of 1st-level or higher double number of damage die rolled for this spell.

The spell's damage increases by 1d6 when you reach 5th level (2d6), 11th level (3d6), and 17th level (4d6).