Casualties of War

Rubbing the powders together, causes them to ignite in your hands. Within your hand bursts a blue flame, choose an area within a 150ft range. From that point, suddenly a 60ft explosion of blue fire bursts out of the ground, shooting blue flames everywhere. Each creature within the original 60ft blast must succeed a Dexterity saving throw with disadvantage. On a failed save a creature takes 10d10 fire damage and half as much on a success.
After that, choose up to 5 locations outside the 60ft blast but that is within 150ft of the chosen spot. Balls of blue fire fall to those spots and explode. Each explosion covers a 20ft range and creatures in the blast must make a dexterity saving throw. On a fail, the creature takes 8d6 fire damage and half as much on a failed save.
The fire spreads around corners and ignites flammable objects in the area that aren't being worn or carried.