d'Cannath's Electifying Smash

The next time you hit a creature with a melee weapon attack during the spell’s duration, your weapon begins to buzz with the current of electricity, and the attack deals an extra 1d6 lightning damage to the target and causes the target's limbs to begin to lock up. The target must make a Constitution saving throw. On a failed save, it becomes paralyzed until the start of your next turn. On a successful save, the spell ends. You have advantage on the attack roll if the target is wearing armor made of metal.

At Higher Levels. When you cast this spell using a spell slot of 2nd level or higher, the initial extra damage dealt by the attack increases by 1d6 for each slot.