The ideal of a Necromancer is to conquer death itself- shatter the mortal coil to see what lies beyond. Usually this results in the goal of Lichdom, but becoming undead isn't the only way to cheat death. Instead of ripping their souls from their living body, they bind their spirits to the mortal plains. Upon death, their souls do not travel beyond the pale, but instead find an empty vessel from which to start anew.

Much of the old soul is lost in this process- some may not even remember their previous lives. However, these sorcerers are seeped in powerful Necromantic energies that strive to preserve the soul within.

Spirit Vessel

Your soul was never meant for the body you inhabit. As such, restorative magics are perverted when they attempt to reach out. 

You cannot receive hit points from any sources that do not affect undead. Instead, you acquire Temporary Hit Points equal to the amount you would have received. These Temporary Hit Points do not stack with Temporary Hit Points from sources not listed in the Arcanolich Origin, but they will stack with each other. You do not become unconscious unless both your hit points and temporary hits are 0, and gaining temporary hit points through Spirit Vessel will bring you back to consciousness. The total amount of temporary hit points you can have at the same time from this effect is equal to your half your maximum hit point total. 

You lose all Temporary Hit Points gained this way at the end of a short or long rest.

Starting at 2nd level, whenever you gain temporary hit points as a result of Spirit Vessel, you can spend 1 Sorcery point to receive additional temporary hit points equal to your spellcasting ability modifier.

Vestiges of Life

The foul magics that anchored your soul still spirals around you like an invisible miasma. Chill air and a sickly scent sticks to this aura you exude, and a sliver of any soul passing through the veil sticks to yours.

Starting at 1st level, whenever a creature that isn't an undead or construct dies within 30 feet of you, gain temporary hit points equal to half your spellcasting modifier (rounded up).

Additionally, whenever a creature more than 30 feet away that isn't an undead or construct is reduced to 0 hit points by damage caused by you, gain temporary hit points equal to your spellcasting modifier.

Temporary hit points gained this way are treated as if gained through Spirit Vessel, and are lost after the end of a short or long rest.

Foul Spell

The dark arts you mastered in your past life have given you the ability to pervert one type of magic with another.

Starting at 6th level, you gain the Foul Spell Metamagic option in addition to other options you have chosen, and whenever you add or replace a spell, you may choose any spell belonging to the Necromancy school and treat it as a Sorcerer spell. You must select a spell of a level which you have spell slots to cast with.

Foul Spell - Imbue your spell with necromantic energy. Spend 3 Sorcery points when a Medium or smaller creature is reduced to 0 hit points as a result of damage from a spell you cast. This creature instantly becomes a Zombie under your control, and retains the initiative roll of the original creature. Any Zombie created this way is active for a number of rounds equal to 1d4 plus half your spellcasting ability modifier (rounded up), and turns to dust after it has expired. This ability has no effect if the target is an undead or construct.

Starting at 12th level, you can instead spend 6 Sorcery points to affect Huge or smaller creatures with Foul Spell.

In addition, add Animate Dead to your list of Spells Known as a Sorcerer spell if you do not already know it. 

Essence Conversion

No aspect of life is beyond utility to you, not even your own.

Starting at 14th level, your flexible casting feature is expanded to include the ability to convert temporary hit points into either Sorcery Points or spell slots, or vice versa. Use the expanded table below to determine the costs:

Temporary Hit Points                   Sorcery Points                     Spell Slot

                 10                                               2                                        1st

                 15                                               3                                        2nd

                 25                                               5                                        3rd

                 30                                               6                                        4th

                 40                                               7                                        5th

 

Everlasting Soul

At 18th level, you have recovered some of the abilities that allowed you your new life.

The first time your hit points becomes 0, you automatically cast a version of Magic Jar as a Reaction without a component cost, treating your unconscious body as the material container.

This version of Magic Jar grants you the following effects:

1. You have advantage on death saving throws as long as you are separated from your body.
2. If the host body dies while you are possessing it, you do not need to make a saving throw to return to your container.
3. If your body returns to consciousness during the duration of this spell, you immediately return to your body and the spell ends.
4. Once you have returned to your body, you gain hit points equal to the number of creatures you successfully possessed x 10.

After this ability has been activated once, it cannot activate again for 24 hours.

In addition, you may add Magic Jar to your list of Spells Known as a Sorcerer spell.