Constantine's Lightning Whip

You weave together static electricity to create a crackling whip of lightning. This magic whip lasts until the spell ends. It counts as a simple melee weapon with which you are proficient. It deals 2d8 damage on a hit, half of which is lightning damage and half of which is magical slashing, and has the finesse, light, and reach properties. In addition, when you use the whip to attack a target that is wearing metal armor, you make the attack roll with advantage.

At Higher Levels. When you cast this spell using a 3rd- or 4th-level spell slot, the damage increases to 3d8. When you cast it using a 5th- or 6th-level spell slot, the damage increases to 4d8. When you cast it using a spell slot of 7th level or higher, the damage increases to 5d8.