Theodorix' Magma

You roar, lifting into the air and channeling the head of Theororix to spew globules of magma. Until the spell ends, you can use your action to unleash magma at a point within range. Each creature in a 15-foot radius around the point must make a Dexterity saving throw. A target takes 5d6 fire damage on a failed save, or half as much on a successful one.
For the duration, any surfaces in the area are covered in magma. A creature that enters the area for the first time on its turn or starts its turn there takes 1d6 fire damage.
At Higher Levels.
When you cast this spell using a spell slot of 5th level or higher, the damage increases by 1d6 for each slot level above 4th.