Beguiling Smite

The next time you hit a creature with a weapon attack before this spell ends, the weapon blurs with a volatile enchantment, ready to vex an unreadied mind. The target hit by the strike takes an extra 3d6 Psychic damage from the attack. Until the spell ends, whenever the target is forced to make a constitution saving throw to maintain concentration on a spell, the DC of that saving throw cannot be lower than the amount of psychic damage dealt to them by this spell.

Using a Higher-Level Spell Slot. The damage increases by 1d6 for each spell slot level above 3.