Pyromancer

Stemming from years of studying Evocation, those who have been drawn like  a moth to a flame have taken the mantle of Pyromancer. You have become one with fire and have learned to harness and bend it to your very will. Pyromancers tend to be more destructive in nature. Often being consumed by the flames and power, but those who have achieved mastery of it can be a powerful ally.  

Warding Flames

 Starting at level 2 when you select this school, you learn to embrace the raging inferno burning around you and become one with it. You are now immune to your own spells that do fire damage, and are resistant to all other sources of the same damage type. Also when you cast a spell that does fire damage that affects other creatures that you can see, you can choose a number of them equal to 1 + the spells level. The chosen creatures automatically succeed on their saving throws against the spell, and they take no damage if they would normally take half damage on a successful save. 

Volatile Blaze

Your fire spells become more dangerous and burn hotter. When you deal fire damage to a single or multiple targets, you can cause the fire to become volatile as a bonus action . Targets hit with Volatile Blaze have the scorched condition for 1D4 rounds (minimum of 1).  While scorched targets become vulnerable to fire damage targets that are normally immune become resistant instead. You can use this feature a number of time equal to your proficiency bonus (minimum 1). You regain all uses of this feature after a long rest.

Ashes to Assets

As a previous Evoker you have become familiar with the arcane sigils used to cast Evocation spells, you have now gained the ability to manipulate and change the sigils to change the damage type of Evocation spells to fire damage. As a bonus action you can change the damage type of Evocation spells to fire damage, you can use this feature a number of time equal to your spellcasting modifier (minimum of 1). You regain all uses of this feature after a short rest.

Incinerate

Your flames have never burned as hot or as bright is they do now, fueled by your passion and desire to pass beyond those before you. Fire begins to encase you for a minute shedding bright light for 30ft around you and dim for an additional 30ft. While in this form you gain the following benefits, you gain temporary hit points equal to 2 times your Wizard level, you temporarily become immune to all fire damage, and lastly all of your spells that do fire damage do and additional 3d6 damage. You can use this feature once a long rest with no negative side effects, if you were to use thus feature again before taking a long rest you will then suffer 2 points of exhaustion, as well as becoming temporarily blinded for the duration of Incinerate and an additional 1d6 rounds afterwards.