Hydaelyn

You create a spherical cage of fire with a radius of 20ft. at a location you can see within range. All creatures in the affected area must succeed on a Dexterity saving throw or take 6d8 fire damage, or half as much on a successful one. The cage persists, allowing you to deal an additional 3d8 fire damage on subsequent turns, and creatures that leave the cage take 2d8 fire damage. When you cast this spell using a spell slot of 6th level or higher, the initial fire damage increases by 1d8 for each slot level above 5th.