concentration, 5 minutes/mana
As two actions, a swirling cloud of smoke shot through with white-hot embers appears in a sphere centered on a point within 20 meters. The cloud spreads around corners and is heavily obscured. It lasts for the duration or until a wind of moderate or greater speed (at least 15 kilometers per hour) disperses it.
A creature that enters the spell’s area for the first time on a turn or starts its turn there must make a Fortitude saving throw.
On a failure, it takes 2d8 fire damage and is burning 1.
On a critical failure, it takes twice as much damage and is burning 2.
On a success, it takes half as much damage and is burning half as much.
On a critical success, it takes no damage.
At the start of each of your turns if the cloud is within 20 meters of you, you can cause it to move up to 2 meters in a direction that you choose. If you spend an action, you can move it up to 10 meters.
Augment
You can increase the damage by 1d8 and the burning level by 1 for every two additional mana expended.
You can expend 1 additional mana so duration changes to 1 hour/mana.