Spellscarred

You have ventured too close to a plagueland and were exposed to the spellplague. You bear an intangible mark that appears only when you use magic, such as a glyph on your forehead or glowing scars on your arms. Whatever the mark, blue fire is a sure indicator of a spellscar. You have gained the ability to transform your attacks, warping mundane fire into an azure flame.

Upon hitting with an attack roll, you may choose to deal fire damage instead of the attack's normal damage type (Proficiency bonus number of uses per Short Rest). Additionally, whenever you deal fire damage, you ignore the target's resistance to fire damage or treat their immunity to fire damage as resistance.