Radiant Soul

Radiant Soul sorceress are well known warriors of light. Burning their enemies with the light within their souls. Fire created from their hands burn brighter than any other. 

May it be through celestial blood, a burning passion or anything like it, light burns within their soul. The body and soul are slowly becoming one through time and experience. 

Body of Radiations

At 1st level, your soul starts becoming one with your body. The light in your soul now covers the other shell of body. This light protects you from flam and light. 

You gain resistance to fire and radiant damage. 

Radiant flame

At 1st level, the fire you create with magic burns more powerful than any other.

You learn the flame bolt cantrip and the burning hands spell these do not count against your spells known. 
Further all spells that deal fire damage change their damage type to radiant damage. 

Light Within

Starting at 6th level, the light that you hold in your soul is brighter than any other. You can burn those that would be resistant and you glow with light of your soul.
You can ignore a creatures resistance to radiant when you cast a spell. 
You can as well use a bonus action to glow bright light for 60 feet and dim light for 30 feet beyond that. You can end with a bonus action. 

Sharing light

At 14th level, your souls light shines brighter than before so much so that you can share that light.

You can grant willing creatures resistance to radiant and fire damage as an action, by spending sorcerer points equal to the amount of creatures you want to gain this benefit. This benefit last for an hour or you can end it as a bonus action

Light beyond

Beginning at 18th level, your soul and body become one. The light in your soul is burning your enemies. 
You gain immunity to radiant damage. 
You as well ignore immunity  to radiant damage and treat is as resistance to it.