Planar Corrupted (Homebrew)

The sorcerer was present at a breach between realms as the planes of Fire and Earth were forcibly brought into the material Plane.  This event scarred their body and soul, granting them magical abilities with special potency in any spell involving fire or earth (bludgeoning damage).  The magical corruption manifests in a tattoo branded into their body that slowly spreads and recedes based on the player's use of extreme magics or allowing the magic to spread out of control.  While this exposure could manifest as Wild Magic, the highly specific nature of the event that granted you powers instead causes amplified spells at the sorcerer's discretion.

Planar Touched

You learn additional spells when you reach certain levels in this class, as shown on the Planar Spells table. Each of these spells counts as a sorcerer spell for you, but it doesn’t count against the number of sorcerer spells you know.

Whenever you gain a sorcerer level, you can replace one spell you gained from this feature with another spell of the same level. The new spell must be an evocation or a transmutation spell from the sorcerer, warlock, or wizard spell list.

Planar Magic Amplification

Elemental energies have flooded your body while in the vicinity of a magical event--the elemental planes melding with the physical world.  The sorcerer's body became unstable, their magics potent, resulting in the mage able to cast spells beyond their normal abilities, albeit at an extreme cost.

At any point, the sorcerer may choose to expend two spell slots of the same level to cast an evocation spell at one higher level; the level of the spell is one more than the spell slots expended, and they must be as high as the sorcerer is capable.  This action also causes the sorcerer to take damage according to level; 1d4 through Level 5, 1d6 through level 10, 1d8 through level 15, 1d10 through level 20.

The planar corrupted may also choose to sacrifice their own energies to fuel their magics; as a bonus action the sorcerer takes scaled damage to regain a spell slot at or lower than the median spell level.  You can use this feature a number of times equal to your Charisma modifier (a minimum of once).  You regain uses of this ability per short rest

Planar Attunement

Starting at 6th level, you gain resistance to fire and bludgeoning damage.  When you cast an Evocation or Transmutation spell that does fire or bludgeoning damage, you may add damage equal to one half your sorcerer level to one damage roll.

Fused with the Planes

At 14th level, you may meld your body to the Planes of Earth and Fire.  As a bonus action you may spend 1 or more sorcery points to channel planar magics into your body for 10 minutes.  For each sorcery point you spend, you may gain one of the following benefits of your choice until the 10 minutes ends:

• Your body melds to the Plane of Earth.  You gain resistance to all slashing, piercing, poison, and lightning damage.  
• Your body melds to the Plane of Fire.  You can teleport your body to an open flame within 120 feet as a bonus action and are immune to fire damage.
• The planar magic amplifies into an aura around you.  When a sorcerer spell dealing bludgeoning or fire damage between 1st and 6th level, you may choose to do maximum spell damage by expending another sorcery point.  The first two uses per long rest will have no adverse effects.  If this feature is used again, the sorcerer must expend an additional spell slot of equal or higher level and take 1d10 necrotic damage.  This damage ignores resistance and immunity.
• You meld your body to both planes of Earth and Fire.  You may compress your form into a molten rock for brief moments to move through spaces as small as 6 inches.  You may spend 10 feet of movement to escape from nonmagical restraints, or being grappled 

Harnessed Magic

At level 18, you have managed to control the surge of planar energies within.  You no longer take damage when overcasting a spell at a higher level.  The sorcerer can also cast a 7th-level spell that does fire or bludgeoning damage without expending a spell slot once per long rest.  

As a reaction, you may expend 2 sorcery points to briefly render your body into flame or rock.  Any non-magical attack will be at disadvantage for this round.