Bottled Lightning

A small glass bottle forms in your hand. Inside the bottle is a shard from the plane of storms, which sends small bolts of lightning arcing across the glass at the smallest disturbance. You can then to  place the bottle on the ground or launch it up to 180 ft, which causes lightning to streak behind the bottle. After 30 seconds on the floor, or after  being launched, the shard becomes unstable and bursts, dealing 3d8 lightning damage in a 30ft emanation around itself and forming any solid surface within into difficult terrain for 1 hour. Any creature in the emanation must make a dex save equal to your spell save DC. On a success, they still take half damage. Any creature that enters or ends their turn in the difficult terrain takes 1d4 lightning damage as the left over residue arcs against them.

At Higher Levels. When you cast this spell using a spell slot of 4th level or higher, the initial damage increases by 1d8 and the difficult terrain damage increases by 1d4 per level past 3rd.