Creeping lightning

You touch the ground with your hand and send a snake-like lightning across it. You get control of the lightning and can control its movement. Lightning can travel a distance of 30 feet as if it were a living being. When lightning touches a creature for the first time, it must perform a Dexterity saving throw. Lightning cannot touch creatures in the air, but it can touch creatures on walls and ceilings if it can get to them. On a failed save, a creature takes 2d8 lightning damage. On a successful save, the creature takes half as much damage.

At Higher Levels. When you cast this spell using a spell slot of 2nd level or higher, the damage increases by 1d8 for each slot level above 1st.

[Tome of spells: Lightning]