You hit a creature, and that creature must succeed on a Intelligent saving throw or be hit by 1d6 Lightning damage. 

At Higher Levels. If you cast this spell using a spell slot at 4th level or higher, you deal 2d6 Lightning damage to 1 foe. If you use a spell slot at 8th level or higher, deal 2d10 Lightning damage to foes within 5 feet of each other.