Ashes

You select a point within range and call forth a devastating pillar of fire that cascades down from the heavens.  Any creature within a 40 foot radius, 1000 foot high cylinder centered on a point within range chosen by the caster must make a dexterity saving throw - a creature takes 30d6 fire damage on a failed save, or half as much damage on a successful one.

The flames consume the area, continuing to burn as long as any creature or targeted object remains within the radius.  The fire will not cease until everything within the area is reduced to ash.  When an object is destroyed or a creature is reduced to 0 hit points by the spell, they are reduced to fine ash.

While the flames persist any creature that starts its turn in the area or enters it for the first time must make a dexterity saving throw, taking 5d6 fire damage on a failed save, or half as much damage on a successful one.  A creature that takes damage from this spell is set ablaze, taking 2d6 fire damage at the start of each of its turns until it or another creature use an action to extinguish the flames,

The spell ends when there are no remaining objects or creatures within the radius to fuel the fire.  Some clerics and divine soul sorcerers are known to cast this spell such that the damage it cause is half fire and half radiant.