Cursing Smite

The first time you hit with a melee weapon attack during this spell's duration, your weapon sings an eerie dirge, and the attack deals 1d12 extra necrotic damage. The target must then succeed on a Charisma saving throw or become cursed until the spell ends.

A cursed creature has disadvantage on attack rolls, and whenever it makes an ability check, an attack roll, or a saving throw that isn't against this spell, it must roll a 1d4 and subtract the number rolled from the result. It repeats the Charisma saving throw at the end of its turns, ending the spell on a success. This debuff does not stack with other similar effects from other spells, such as the Bane spell.

Using a Higher-Level Spell Slot. The damage increases by 1d12 for each spell slot level above 2.