Unholy

An unholy sorcerer is one who has taken the first steps towards lichdom, but has either failed or not yet attempted the full ritual. Be it through lack of skill, knowledge, power or preparation, the full ascension did not work out as planned, but was not without its fruits. Harboring the necromantic energies of undeath within their body, they command undeath like a bard their lute or a monk their fists.

Necromantic Aura

When a humanoid creature of size Medium or smaller dies within 30 ft. of you, you can use your reaction to spend one sorcery point to animate it immediately. The creature uses the 'Zombie' monster's stat block, but only has 1 hit point and an Armor Class of 10.  The animated corpse exists for up to 1 minute before turning into dust. The creature's CR must be equal to or lower than 1/3rd of your sorcerer level. You may command all your undead thralls with a single bonus actions, upon which they will all attempt to make that action, or you can command one individually.

At third level, you can resurrect any type of creature of Medium or smaller size. 

At sixth level, the creature keeps its stats as it had in life, but makes all attacks at disadvantage, has an Armor Class of maximum 11 and has only 1/4th of its original maximum hit point total. The reanimation lasts for 10 minutes. 

At 9th level, you can reanimate creatures of size Large in addition to the smaller sizes. The reanimation lasts for 1 hour.

At 13th level, the creature retains its statistics as it had in life. The reanimation lasts for 24 hours. You may now resurrect creatures with a CR of up to half your sorcerer level.

At 16th level, you can reanimate creatures up to Huge size and every undead controlled by you lasts for at least 1 week. They use the stats they had in life and gain the 'Undead Fortitude' trait.

At 20th level, you can reanimate whatever creature and they do not decay. You may animate creatures of whatever CR, but for every CR about 10 you must spend an additional day pouring magic into the creature.

Strength of the Grave

Starting at 1st level, your existence in a twilight state between life and death makes you difficult to defeat. When damage reduces you to 0 hit points, you can make a Charisma saving throw (DC 5 + the damage taken). On a success, you instead drop to 1 hit point. You can’t use this feature if you are reduced to 0 hit points by radiant damage or by a critical hit.

After the saving throw succeeds, you can’t use this feature again until you finish a long rest.

Unholy Bonds

When you cast a spell that would allow you to resurrect a creature into undeath, you can target twice the amount of creatures as normal. The period they are under your control is doubled and once the period passes, they must make a Charisma saving throw against your spell save DC before they are freed from their bonds.

Essence Siphon

You gain resistance to necrotic damage. When you kill an enemy with a Necromancy-school spell, you gain an amount of hit points equal to excess damage that spell dealt, up to a maximum of the amount of hit points the enemy had remaining before you dealt the final blow.

At The Brink

At 18th level, you have started the final step into achieving lichdom. You count as both humanoid and undead. You have advantage on saving throws that would turn undead.

As an action, you can spend 6 sorcery points to briefly force your way into full lichdom, for up to one minute. Whilst in this form, you are immune to necrotic damage, vulnerable to radiant damage and gain the use of one Legendary Action and one Legendary Resistance. You can transform once per long rest.