As two actions, a fountain of molten lava erupts from a point on the ground within 20 meters. The ground in that area becomes difficult terrain until cleared. Each 1-meter square portion of the area requires at least 1 minute to clear by hand. Each creature in a cylinder centered on that point must make a Reflex saving throw.
On a failure, it takes 5d6 fire damage and is burning 2.
On a critical failure, it takes twice as much damage and is burning 4.
On a success, it takes half as much damage and is burning 1.
On a critical success, it takes no damage.
You can increase the damage by 1d6 and the burning level by 1 for each additional mana expended.