Combusting Wave

You strike the ground, creating a scorching wave of elemental fire energy that ripples outward from you. Each creature you choose within 30 feet of you must succeed on a Constitution saving throw or take 10d6 fire damage, and be knocked prone. A creature that succeeds on its saving throw takes half as much damage and isn’t knocked prone.

The wave damages and ignites flammable objects in the area that aren't being worn or carried.

At Higher Levels. When you cast this spell using a spell slot of 6th level or higher, the damage increases by 1d6 for each slot level above 5th.