Hungering Soul

Your magical power originates from the Plane of Negative Energy, or perhaps stems from a lineage steeped in Vampirism or Lichdom with the stench of Undeath persisting across generations. You may have once been exposed to the elements of the Plane of Negative Energy and were corrupted by it, or perhaps a god or goddess of death has left a mark upon you. Whatever the case, your soul is tainted with an innate desire to consume the life force of others, wielding it as a weapon to augment your own arcane powers. Not innately evil, some Sorcerers may learn to master this power to aid others and crush their enemies upon the battlefield. Whatever the circumstances that causes your soul to lash out with hunger and anguish, you are forever changed.

Extract Essence

Starting at 1st level once per turn, when you reduce a hostile enemy to 0 hit points or roll a critical hit with a sorcerer spell you gain temporary hit points equal to your Charisma modifier. (minimum of 1). These temporary hit points persist until the end of your next long rest.

Otherworldly Endurance

Starting at 1st level, once per day when you are reduced to 0 HP, you can roll your first death saving throw with advantage. Furthermore, if you roll a 20 on a death saving throw you gain an additional amount of hit points equal to your Charisma modifier (minimum 1).

Lethargy

At 6th level, once per short rest when an enemy fails a saving throw by 5 or more or rolls a natural one against one of your sorcerer spells or subclass features, you can choose either for them to take one level of exhaustion (maximum of three levels) or grant you advantage on your next ability check or ranged spell attack roll until the end of your next turn.

Revitalize

At 14th level once per long rest, you gain the ability to consume fragments of a fallen foe's soul to revitalize your own body. After reducing a hostile enemy to zero hit points, as an action you can choose to expend 7 sorcery points, and temporarily halt the effects if aging for one year as well as cure one of the following conditions for yourself blinded, deafened, up to one level of exhaustion, poisoned. You can also expend these benefits to an ally of your choice by expending 10 sorcery points. In addition, you also regain hit points equal to your Sorcerer level + your Charisma modifier (minimum 1).

Veil of Souls

Starting at 18th level, you can spend 6 sorcery points, to attempt to magically assume the appearance of a humanoid within 30ft of you by siphoning a portion of their soul. The target must make a Charisma saving throw against your spell save DC. On a failed save,  you assume their appearance for up to 24 hours while they become Incapacitated for the duration. While disguised, you have advantage on Charisma (Deception) checks and Charisma (Performance) checks to pass yourself off as that person. On a success, the target takes 2d8 necrotic damage. The target automatically fails the saving throw if they have been killed within the last minute, allowing you to assume their appearance.