Hogwarts schooling

You create a ringed wall of fire within range up to 20 feet in diameter, 20 feet high, and 10 feet thick choosing whether it's touching the ground or in the air. The wall is opaque and lasts for the duration. When the wall appears, each creature within its area must make a Dexterity saving throw. On a failed save, a creature takes 4d8 fire damage, or half as much damage on a successful save. A creature takes the same damage when it enters the wall for the first time on a turn or ends its turn there.