Phoenix Primal

Your innate magic comes from primal magic that was mingled with the blood of your ancestors. You must be a Fire Genasi to chose this subclass and most often a direct linage from a powerful entity from the plane of fire. One of your parents were likely an Efreeti or maybe a Phoenix in human form. In either case the fury of their coupling has tempered you to this power source of magic, and as a moth to the flame it entices you to discover more.

Restriction: Fire Genasi Only

Only a Fire Genasi is capable of pursuing the elemental mastery of the Plane of Fire. It is a natural born connection to the Plane where the Fire Genasi draw their power from.

Your DM can lift this restriction to better suit your campaign. The restriction reflects the trials of a Fire Gensai with natural born ties to the elemental Plane of Fire, but it might not apply to your DM's setting or your DM's version of the Planes.

The Dervish Blade

You have been trained to use a scimitar in a lethal fiery dance. You gain proficiency with both the performance skill and scimitars, which you can also use as an arcane focus. When you attack with a scimitar, you can use your Charisma modifier, instead of Strength or Dexterity, for the attack and damage rolls.

Conflagrative Magic

Starting at 1st level, you can use a bonus action on your turn to cause the air around you to become alarmingly hot, immediately before or after you cast a spell of 1st level or higher. Doing so allows you to impose disadvantage on melee attacks against you for one minute. Can be used once per long rest. (5th level - 3 uses, 11th level - 5 uses)

Heart of the Sun

At 6th level, you gain immunity to fire damage. In addition, whenever you start casting a cantrip spell that deals fire damage and you are wielding a scimitar, fire races through your veins and you may move an additional ten feet. If you move, you gain a bonus to your armor class equal to your Charisma Modifier until the start of your next turn and you can make a melee weapon attack with your scimitar as a bonus action. If you hit with the attack the opponent takes additional fire damage equal to your Charisma Modifier as the blade of your scimitar becomes super heated and glows fiery red.

Let 'em Burn

At 6th level, your fire spells have risen in intensity, but you have also learned to control it.

Spells you cast ignore fire resistance. In addition, when you roll damage for a spell you cast that deals fire damage, you can treat any 1 on a damage die as a 2.

If you have careful spell metamagic option, then if you cast any fire based spell that includes the creatures selected they also take no damage if they would normally take half damage on a successful save. In fact, instead each creature in the spell's area of effect also gain temporary hit points equal to half your sorcerer level (rounded down) + your Charisma modifier as you temper them with fire. A creature can't gain temporary hit points from this feature again until it has finished a short or long rest.

Inferno’s Fury

Starting at 14th level, your fire based spells now ignore fire immunity, except you of course. Also, whenever you are hit by a melee attack, you can use your reaction to deal fire damage to the attacker. The damage equals your sorcerer level. The attacker must also make a Strength saving throw against your sorcerer spell save DC. On a failed save, the attacker is pushed in a straight line up to 20 feet away from you.

Immolation of the Phoenix

At 18th level, your natural connection to the Plane of Fire grants you the Immolation of the Phoenix. This ancient method of binding your soul had been banned and nearly forgotten for millennia. It ties your soul to the ever-burning flames of the Plane of Fire, and keeps your soul alive for as long as the flames stay burning. This connection grants you the ability to summon flaming phoenix wings from your back, granting you a 60 ft. fly speed. During this you can summon the destructive force of the phoenix and cast the Waves of Destruction spell once per long rest.

Also, with your soul now intertwined with the flames of the Plane of Fire, you no longer age physically, nor can you die of old age. If you die, roll a D20. If it is a 10 or higher, your physical body turns to ash and all of your belongings disappear in a flash of fire. You reappear 1+1D3 days later in the Plane of Fire, your body slightly charred, but having gained the benefits of a long rest.