Volatile Pyromancer

Born with a powerful Efreet soul attached to theirs, the Volotile Pyromancer sit on the verge of breaking, their vessal generally not powerful enough to hold the soul back.

Volatile Soul

As you release fire, the one within you grows. Everytime you cast a fire based spell you gain stacks of Inner Flame equal to the spells level. Your fire based spells deal extra damage equal to the stacks. 

Each time you cast a fire based spell you must make a DC5+Inner Flame stacks Con Save. On a failed save you detonate, dealing 1d4 fire damage per Inner Flame stack to everything in a distance equal to the Inner Flames stacks rounded up.

5/6 discharge: During a long rest, if you roll a 5 or 6, you discharge 1d3 stacks of Inner Flame.

This feature does not effect cantrips.

Quick Release

Spending a Sorcery Point per level, you may cast a fire based spell as a bonus action instead.

You also gain resistance to fire damage.

Controlled Flame

Once per long rest, you may expend 1d6 inner flame stacks. You may choose to: Fire a beam in a 30ft line, shoot a 15ft cone of flame or detonate in a 10ft area around you. Each creature hit must make a Dexterity Saving Throw against your spell save DC, taking 1d6 fire damage per inner flame stack expended on a failed save, or half on a successful save.

This increases to 1d8 stacks at 16th level.

Super Nova

At 18th level you learn to release the fire within in a devistating explosion. Expend all inner flame stacks, dealing 1d10 fire damage per stack to all creatures with a radius equal to the stacks rounded up to the nearest 5.

This causes 1 point of exhaustion.