As an action, make a weapon attack.
On a hit, add 1d6 + your spellcasting ability necrotic damage to the attack’s damage roll and the creature must succeed on a Fortitude saving throw or its eyes or ears are engulfed in shadow as it is either blinded or deafened (your choice) for the duration.
On a critical hit, add twice as much damage.
On a miss by 4 or less, add half as much damage.
The creature can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success.
You can increase the damage by 3d6 for each additional mana expended.