Incendiary Cloud

A swirling cloud of smoke shot through with white-hot embers appears in a 20-foot-radius sphere centered on a point within range. The cloud spreads around corners and is heavily obscured. When the cloud appears, each creature in it must make a Dexterity saving throw, taking 10d8 fire damage on a failed save, or half on a success. A creature must also make this saving throw when it enters the spell's area for the first time on a turn or ends its turn there.