Electric Fence

You create an invisible, spherical perimeter around a point you can see within range. The area has a radius of 15 feet. Whenever a creature would enter or leave this area without teleporting, the spell delivers an electric shock.

An affected creature must make a Constitution saving throw. On a failed save, the creature takes 3d8 lightning damage and until the beginning of its next turn its speed is reduced to 0 and it can't gain any bonuses to its speed. This occurs before the creature crosses the threshold. On a successful save, the creature takes half as much damage and its movement is not impeded.

At Higher Levels. When you cast this spell using a spell slot of 4th level or higher, the damage increases by 1d8 for each slot level above 3rd.