STR	DEX	CON	INT	WIS	CHA
14 (+2)	12 (+1)	12 (+1)	5 (-2)	8 (-1)	6 (-2)

Necromancer

Robes billowing around him, a human stands atop a hill watching legions of unholy march towards a city in the dead of a night. As the front lines reach the gates an alarm goes off within the city, but it was too late. The city is surrounded, and there’s no help coming.

With her scythe cutting through the last stalk of wheat, an elf wipes the sweat from her brow and takes a moment to observe her undead friends in front of her, all with scythes cutting wheat themselves. Out of the corner of her eye, she notices a ghoul shambling over a nearby hill. With a quick glare from the elf, the ghoul stops and turns around, reporting to her that there is an army following it. The elf takes off running with what wheat she has and the skeletons follow her.

A halfling kneels behind a column at the dead body of his best friend, a dwarf. Crying, he reaches out to the body and mutters disdainfully. He asks out loud if his friend would lend him his strength so that one of them might be able to live. After a few seconds, his friend stands up once again and charges a nearby goblin, buying the halfling just enough time to get away. He runs back to town just in time to warn them of the coming goblin horde.

Necromancers channel the power of life and death. They may be weak themselves, but they make up for it by surrounding themselves with undead minions that they control as if they were an extension of the necromancer’s own body. Necromancy is not something people undertake lightly, as a false step in the wrong company may cause one to lose their head.

Undead Minions

Necromancers exert control over undead creatures as if they were part of the same creature. Unlike hordes of wild undead, the undead controlled by a necromancer act as one unit, often running or shambling to each other’s aid when a member of the horde is injured or destroyed.

A Life of Consequences

Necromancers don't have the best history with people. Though the large majority of necromancers merely want to help people, whether it be in communicating with dead family members or overthrowing tyrannical kings, evil necromancers are by far more well known for the occasional invasion of a peaceful city, which people do not tend to take kindly to. A necromancer must always be careful of his company, because while some people will seek to understand his intentions, just as many will ignore them altogether in the assumption he is pure evil.

Creating a Necromancer

The most important thing to consider when creating a necromancer are the reasons you became a necromancer. Were you driven to the edge when someone you love was killed or did an oppressive government lead to your seeking rebellion? Either way, a necromancer is often misunderstood by those around them. Necromancers must usually hide their abilities to avoid persecution.

Quick Build

You can make a Necromancer quickly by following these suggestions. First, make Intelligence your highest ability score, followed by Constitution, and Strength or Dexterity after that if you plan on taking the Reaper Archetype. Second, choose the Sage background.

Class Features

As a Necromancer, you gain the following class features

Hit Points

Hit Die: 1d6 per Necromancer level
Hit Points at 1st Level: 6 + your Constitution modifier
Hit Points at Higher Levels: 1d6 (or 4) + your Constitution modifier per Necromancer level after 1st

Proficiencies

Armor: No armor
Weapons: Simple weapons
Tools: Poisoner's Kit

Saving Throws: Constitution, Intelligence
Skills: Choose two from Arcana, Deception, History, Insight, Intimidation, Medicine, Persuasion, and Religion

Equipment

You start with the following equipment, in addition to the equipment granted by your background:

(a) Darkened robes and two daggers or (b) a light crossbow, simple clothes and 20 bolts
(a) An arcane focus and poisoner's kit
(a) a dungeoneer’s pack or (b) a scholar’s pack

Alternatively, you may start with 5d4 × 10 gp to buy your own equipment.

Multiclassing

Prerequisites. To qualify for multiclassing into the necromancer class, you must meet these prerequisites: Constitution and Intelligence 13.

Necromancer

Level	Proficiency Bonus	Features	Cantrips Known	1st	2nd	3rd	4th	5th	6th	7th	8th	9th
1st	+2	Spellcasting, Arise and Obey	3	2	—	—	—	—	—	—	—	—
2nd	+2	Undying Ambitions	3	3	—	—	—	—	—	—	—	—
3rd	+2	Necromantic Aspiration	3	4	2	—	—	—	—	—	—	—
4th	+2	Ability Score Improvement	4	4	3	—	—	—	—	—	—	—
5th	+3	Wicked Amendments	4	4	3	2	—	—	—	—	—	—
6th	+3	Aspiration Feature	4	4	3	3	—	—	—	—	—	—
7th	+3	─	4	4	3	3	1	—	—	—	—	—
8th	+3	Ability Score Improvement	4	4	3	3	2	—	—	—	—	—
9th	+4	─	4	4	3	3	3	1	—	—	—	—
10th	+4	Aspiration Feature	5	4	3	3	3	2	—	—	—	—
11th	+4	─	5	4	3	3	3	2	1	—	—	—
12th	+4	Ability Score Improvement	5	4	3	3	3	2	1	—	—	—
13th	+5	─	5	4	3	3	3	2	1	1	—	—
14th	+5	Aspiration Feature	5	4	3	3	3	2	1	1	—	—
15th	+5	─	5	4	3	3	3	2	1	1	1	—
16th	+5	Ability Score Improvement	5	4	3	3	3	2	1	1	1	—
17th	+6	─	5	4	3	3	3	2	1	1	1	1
18th	+6	─	5	4	3	3	3	3	1	1	1	1
19th	+6	Ability Score Improvement	5	4	3	3	3	3	2	1	1	1
20th	+6	Unholy General	5	4	3	3	3	3	2	2	1	1

Spellcasting

As an adept of dark arts, you have a Grimoire containing Spells that show the first glimmerings of your true power.

Cantrips

At 1st level, you know three cantrips of your choice from the necromancer spell list. You learn additional necromancer cantrips of your choice at higher levels, as shown in the Cantrips Known column of the Necromancer table.

Grimoire

At 1st level, you have a Grimoire containing six 1st-level necromancer spells of your choice. Your Grimoire is the repository of the necromancer spells you know, except your cantrips, which are fixed in your mind.

Preparing and Casting Spells

The Necromancer table shows how many spell slots you have to cast your spells of 1st level and higher. To cast one of these spells, you must expend a slot of the spell's level or higher. You regain all expended spell slots when you finish a long rest.

You prepare the list of necromancer spells that are available for you to cast. To do so, choose a number of necromancer spells from your Grimoire equal to your Intelligence modifier + your necromancer level (minimum of one spell). The spells must be of a level for which you have spell slots.

For example, if you're a 3rd-level necromancer, you have four 1st-level and two 2nd-level spell slots. With an Intelligence of 16, your list of prepared spells can include six spells of 1st or 2nd level, in any combination, chosen from your Grimoire. If you prepare the 1st-level spell magic missile, you can cast it using a 1st-level or a 2nd-level slot. Casting the spell doesn't remove it from your list of prepared spells.

You can change your list of prepared spells when you finish a long rest. Preparing a new list of necromancer spells requires time spent studying your Grimoire and memorizing the incantations and gestures you must make to cast the spell: at least 1 minute per spell level for each spell on your list.

Spellcasting Ability

Intelligence is your spellcasting ability for your Necromancer Spells, so you use your Intelligence whenever a spell refers to your spellcasting ability. In addition, you use your Intelligence modifier when Setting the saving throw DC for a Necromancer spell you cast and when Making an Attack roll with one.

Spell Save DC = 8 + your proficiency bonus +

your Intelligence modifier

Spell attack modifier = your proficiency bonus +

your Intelligence modifier

Ritual Casting

You can cast a Necromancer spell as a ritual if that spell has the ritual tag and you have the spell in your Grimoire. You don't need to have the spell prepared.

Spellcasting Focus

You can use an arcane focus (found in chapter 5) as a spellcasting focus for your necromancer spells.

Learning Spells of 1st Level and Higher

Each time you gain a Necromancer level, you can add two Necromancer spells of your choice to your Grimoire. Each of these spells must be of a level for which you have spell slots, as shown on the Necromancer table. On your adventures, you might find other spells that you can add to your Grimoire

Arise and Obey

Starting at 1st level you can animate recently slain corpses. As an action, you can touch a corpse of non-construct creature that has died in the last minute and raise it as an Restless Servant controlled by you. Creature uses your proficiency bonus and spellcasting modifier in it's statistics.

You may have number of controlled Restless Servants with this feature equal to your half of Proficiency modifier (rounded up). If you attempt to rise servant above limit, oldest servant crumbles into pile of bones or rotten flesh.

In combat, they act right after your turn. You can direct the actions of all undead creatures under your control that you can see as an action on your turn, and they will attempt to execute your last orders to the best of their ability.

You also innately know the general direction and distance of all your Restless Servants. You can maintain control of your minions as long as they are within 1 mile of you. If they leave this 1 mile radius, they leave your control and act as a wild undead creatures.

Restless Servant

Up to medium size Undead, Neutral Evil

Armor Class 10 (12 if Putrid) + your Proficiency Bonus

Hit Points 10 + necromancer level (5 + necromancer level if skeletal)

Speed 30ft

STR DEX CON INT WIS CHA

14 (+2) 12 (+1) 12 (+1) 5 (-2) 8 (-1) 6 (-2)

Saving Throws none

Skills none

Damage Vulnerabilities none

Damage Resistances none

Damage Immunities Poison

Condition Immunities Poisoned, Exhaustion

Senses Darkvision 60ft

Languages understands all languages it spoke in life but can't speak

Body Structure Type (Choose One).
Skeletal - Creature gains proficiency in Dexterity saving throws and can use Necrotic Bolt attack
Putrid - Creature gains proficiency in Constitution saving throws and it's Claw/Bite attack can poison the target

Actions

Claw/Bite. Melee Weapon Attack: +Spellcasting Bonus to hit, reach 5 ft., one target. Hit: 1d8 + Proficiency Bonus piercing or slashing damage (your choice). (Putrid Only) - target also makes constitution saving throw against your spell save DC or becomes poisoned until the start of your next turn
Necrotic Bolt. (Skeletal Only) Ranged Spell Attack: +Spellcasting Bonus to hit, range 30\60 ft., one target. Hit: 1d6 + Proficiency Bonus necrotic damage

Undying Ambitions

Upon reaching the 2nd level, your frequent experiments and interactions with the undead have left their mark. Your body is now suffused with negative energy that helps you even on the bring of death.

You can add your proficiency bonus to any death saving throw you make. Moreover, whenever a creature within 30 feet of you rolls 1 on death saving throw counts as only 1 failure.

Necromantic Aspiration

At 3rd level choose a Necromantic Aspiration: Flesh Sculptor, or Soul Weaver. All detailed information is at the end of the class description. Your choice grants you features at 3rd level, and again at 6th, 10th, and 14th level.

Ability Score Improvement

When you reach 4th level, and again at 8th, 12th, 16th, and 19th level, you can increase one ability score of your choice by 2, or you can increase two ability scores of your choice by 1. As normal, you can’t increase an ability score above 20 using this feature.

Wicked Amendments

Starting at 5th level, you improve the creation and manipulation of your own servants, experimenting and endowing them with new properties.

You now can use Arise and Obey feature if a creature has been dead for longer than 1 minute. you must spend an hour concentrating (as if concentrating on spell) in order to raise it.

Also, you learn 2 Wicked Amendments from the list that you can find below. You learn 2 new amendments at 9th and 13th levels. You can replace up to 2 known amendments with 2 amendments from the list whenever you gain level in this class.

Whenever you rise Restless Servant, you can add 1 known amendment to empower it. You can change applied amendments on your Servants at the end of your long rest. Creatures cannot have more that 1 amendment at the same time. maximum amount of amendments on a creature increases at 2 at 13th level.

Wicked Amendments List

Undying Fortitude

If damage reduces Servant to 0 hit points, it must make a Constitution saving throw with a DC of 5 + the damage taken, unless the damage is radiant or from a critical hit. On a success, the it drops to 1 hit point instead.

It also increases its Constitution Score to 12.

Reaping Limbs

Reach of creature's melee attack is increased by 5 feet. Creature's ranged attacks ignore half-cover. Whenever creature hits with attack, it deals extra 1d4 necrotic damage.

Developed Consciousness

Creature's Intelligence, Wisdom and Charisma increased to 10. It is able to speak and perform complex tasks such as attempting to lockpick the lock or bake a cake. If there is no organ capable of speaking, it's voice echoes from it's body. At DMs discretion Servant may recall some fragments of last moments from it's life. You and Servant can communicate telepathically with each other while it is within 1 mile of you.

Horrific Visage

Creature can use your spellcasting modifier instead for Intimidation checks it makes. Also, once per long rest, as an action you can command it to let out a terrifying howl or give off a frightening aura forcing each creature of your choice within 30 ft of it to make Wisdom Saving Throw against your Spell Save DC. On Failure, creatures are frightened by your Servant for next minute. They can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success.

Shadowfell's Nature

Creature can attempt to hide as bonus action while in dim light or darkness. It also can move through other creatures and objects as if they were difficult terrain while in dim light or darkness. It takes 5 (1d10) force damage if it ends its turn inside an object. While in solid objects such as walls, it can move freely within that object. It can't make actions beside Hide while being in solid objects.

Relentless Predator

Creature's movement speed is increased by 10ft. It also gains swimming and climbing speed equal their movement speed. If Servant moves at least 20 feet straight toward a creature and then hits it with a Claw\Bite attack on the same turn, that target must succeed on Strength saving throw against your Spell Save DC or be knocked prone.

Unholy General

At 20th level you have uncovered dark secrets that infused your soul with a near infinite amount of necrotic energy, becoming the source of your very lifeforce.

you no longer have a limit on the number of Restless Servants you can control. You also do not lose control over the undead creatures you control, regardless of distance or difference in planes of existence.

Moreover, issuing commands to your undead creatures has no action requirement.

Necromantic Aspirations

Necromancers share their affinity with undead, but how they use their undead often varies. Some Necromancers tend carefully to their undead minions while some Necromancers are able use the souls of the departed as a source of energy.

Flesh Sculptor

While other necromancers use necromantic magic to gain power over death, you have always been more fascinated with the workings of unlife. Through years of experimentation, you have learned not only how to raise and dominate the undead, but also to preserve, train, and improve them far beyond their usually meager abilities.

Caretaker

Starting at 3rd level, Your commitment to the care and quality of your creations allows you to create more finely crafted creatures.

Whenever you gain control over undead creature, it's maximum hit points is increased by of your necromancer level. All non-hostile undead creatures within 10 feet of you rolls with advantage d20 tests against Turning effects, such as Channel Divinity: Turn Undead.

Restless Servitude

At 6th level, you add the Summon Undead spell to your grimoire if it is not there already. Undead Spirit summoned with this spell by you counts as Restless Servant for all effects that applies to them, but does not count towards your total amount of Restless Servants determined by Rise and Obey feature.

Moreover, you now can issue commands to undead creatures under your control through Rise and Obey feature as bonus action instead.

Limitless Perfection

Beginning at 10th level, you have spent so much time dealing with undead and the forces that animate them so that your art of creating majestic carcasses can be truly terrifying for the untrained eye.

Your Restless Servants can now have 2 amendments at the same time. Also, during a short rest you can reconstruct your Restless Servant, changing applied Amendment to other known one. Each reconstruction takes 10 minutes of short rest.

Magnum Opus

Starting at 14th level, for only a glimpse of moment, you can create a terrifying fusion of your servants into something... magnificent.

As an action, you can choose 3 Restless Servants under your control within 30ft of you to temporary fuse them into an Undead Abomination that appears in an unoccupied 5 or 10 foot space (depends on chosen size) within the specified radius. Selected servants transforms into Unholy Abomination that uses Flesh Golem statistic. It is under your control for 1 minute and has additional effects:

Size of Unholy Abomination increases to Large, if space allows it.
You decide how the Uholy Abomination you create looks like, be it a bone mass, a rotten giant, or any other image that suits you.
Uholy Abomination gains temporary hit points equal to your necromancer level
Uholy Abomination uses your spellcasting modifier for attack rolls and adds your proficiency bonus to it's damage damage rolls
Whenever Uholy Abomination activates Berserk feature, it will attempt to attack only nearest creatures that you consinder as your enemy.
Whenever Uholy Abomination's Hit Points lowers to 0 or after 1 minute it disintegrates into 3 piles of rotten flesh and bones.

Once you use this feature, you can't use it again until you finish a long rest.

Soul Weaver

Soul Weavers focus on controlling the powers of souls, the most dangerous yet most powerful aspect of necromancy. They are masters at controlling and manipulating souls, knowing how to imprison them or tear them apart for use as fuel in their dark magic and spells.

Dark Lore

Starting at 3rd level, due to your extensive knowledge of Necromancy, you gain advantage on any Religion and Arcana checks related to necromantic spells, rituals or undead creatures.

Moreover, you learn 2 necromancy spells of your choice from any class, A spell you choose must be of a level you can cast, as shown on the Necromancer table, or a cantrip. The chosen spells count as Necromancer spells for you but don't count against the number of bard spells you know.

You learn 1 additional necromancy spell from any class at 5th, 9th, 14th and 17th levels.

Undying Nature

At 6th level, the time you've spent wielding necrotic energy has made itself a part of you. you can hold your breath indefinitely, and you don't require food, water, or sleep, although you still require rest to reduce exhaustion and still benefit from finishing short and long rests. You also age at a slower rate. For every 10 years that pass, your body ages only 1 year, and you are immune to being magically aged.

Moreover, whenever you receive damage and you have your Restless Servant withint 30ft of you, as a reaction you can force this damage to be dealt to your Servant instead.

You can redirect damage with this feature twice, and you regain any expended uses when you finish a long rest.

Circle of Lifeforce

Beginning at 10th level, whenever you deal necrotic damage with a spell of 1st level or higher, as a bonus action you can choose a creature other than you within 30ft. It regains 1d4 + your spellslot level hit points. If target is Undead Creature, it doubles the amount of heal.

Gaze of Death

Starting at 14th level, your gaze can awaken the sense of mortality in a creature by giving them visions of their death, shaking their very soul.

As an action choose a creature within 30 feet that you can see. The target must succeed on a Wisdom saving throw against your Necromancer spell save DC or become frightened for 1 minute. The frightened target can repeat its saving throw at the end of each of its turns. On a success the target suffers no effects and is immune to this feature for next 24 hours.

Balance Thoughts

Unfortunately, having multiple creatures under your control in 5th edition of D&D can be very unbalanced. Even though i have tried to balance it as much as i could without ruining fun of playing with more than 2-3 minions, this class can possibly break the balance of the game, if a player tries to maximally optimize it. I STRONGLY recommend to forbid multiclassing with or into this class

Credits

Created by /r/SamuelWillmore
Credits to all of the arts:

All Liliana Vess arts by WotC

Skeleton art by WotC

Lich by The Battle for Wesnoth Project

Special Thanks

Thanks to /r/UnearthedArcana, /r/McLellanCM, u/Squ4tch_ and TheDiscordOfManyThings, for giving me feedback and helping me balancing this class.

Necromancer Spell List

Cantrips (0 Level)

Acid Splash
Chill Touch
Dancing Lights
Frostbite (XG)
Green-Flame Blade (SC)
Infestation (XG)
Mold Earth (XG)
Poison Spray
Ray of Frost
Spare the Dying
Sword Burst (SC)
Thaumaturgy
Toll the Dead (XG)
True Strike
Thunderclap
Tasha's Caustic Brew (TCE)
Lightning Lure
Minor Illusion
Message

1st Level

Bane
Cause Fear (XG)
Command
Mage Armor
Detect Evil and Good
Detect Poison and Disease
Disguise Self
Inflict Wounds
Protection from Evil and Good
Shield
Ray of Sickness
Hex
Purify Food and Drink
Identify
Magic Missile
Detect Magic
Comprehend Languages
Alarm
Grease

2nd level

Aid
Augury
Blindness/Deafness
Blur
Borrowed Knowledge (SCC)
Darkness
Gentle Repose
Lesser Restoration
Vortex Warp (SCC)
Web
Wither and Bloom (SCC)
See Invisibility
Shadow Blade (XG)
Rime's Binding Ice (FTD)
Phantasmal Force
Melf's Acid Arrow
Ray of Enfeeblement
Arcane Lock
Flaming Sphere
Misty Step
Detect Thoughts
Hold Person
Nystul's Magic Aura
Enlarge/Reduce
Scorching Ray

3rd Level

Animate Dead (read below)
Antagonize (BMT)
Blink
Fear
Feign Death
Magic Circle
Phantom Steed
Remove Curse
Revivify
Speak With Dead
Spirit Shroud (TCE)
Summon Undead (TCE)
Vampiric Touch
Hypnotic Pattern
Counterspell
Enemies Abound (XG)
Dispel Magic
Fireball
Lightning Bolt
Leomund's Tiny Hut

4th Level

Arcane Eye
Evard's Black Tentacles
Blight
Death Ward
Locate Creature
Mordenkainen’s Private Sanctum
Leomund's Secret Chest
Phantasmal Killer
Shadow of Moil (XG)
Sickening Radiance (XG)
Spirit of Death (BMT)
Banishment
Dimension Door
Otiluke's Resilient Sphere
Vitriolic Sphere
Arcane Eye
Dominate Beast

5th Level

Danse Macabre (XG)
Antilife Shell
Contagion
Dream
Dimension Door
Hallow
Negative Energy Flood (XG)
Raise Dead
Rary's Telepathic Bond
Enervation (XG)

6th Level

Circle of Death
Create Undead (read below)
Disintegrate
Eyebite
Harm
Arcane Gate
Magic Jar
Move Earth
Soul Cage
True Seeing

7th Level

Power Word Pain (XG)
Etherealness
Finger of Death
Forcecage
Resurrection
Symbol
Delayed Blast Fireball
Dream of the Blue Veil (TCE)

8th Level

Abi Dalzim’s Horrid Wilting (XG)
Maddening Darkness (XG)
Demiplane
Feeblemind
Mighty Fortress (XG)
Antimagic Field
Maze

9th Level

Astral Projection
Blade of Disaster (TCE)
Psychic Scream (XG)
Power Word Kill
Wish
Gate
Imprisonment
True Resurrection
Time Stop

(XG) - Xanathar's Guide to Everything
(TCE) - Tasha's Cauldron of Everything
(FTD) - Fizban's Treasury of Dragons
(SCC) - Strixhaven: A Curriculum of Chaos
(BMT) - The Book of Many Things

Animate Dead and Create Undead spells can only be allowed by DM. It is highly recommended to use Minion rules from "Flee Mortals!" by MCDM Productions for creatures under player's control created by these spells.

Optional Feature

Becoming a Lich

If a player would like to become Lich to represent his character progression, here is Mechanic that will allow you to become Lich, without ruining DM's balance. Still, it is strongly recommended to provide this feature as a late-game ability.

To become a Lich, You must complete a 24 hour ritual, concentrating on it as if you where concentrated on a spell. For this ritual you will need to create Phylactery at first, that is needed for your further existence. As a ending part of a ritual, you can cleanse yourself of the flesh, that will be transformed into a life force which infuses your Phylactery.

Whenever you are done the ritual, you undergone significant changes, gaining such benefits:

Your type changes to undead. All spells and effects that would apply to undead creatures apply to you. As an undead, you do not need to breathe or sleep, you cannot suffocate, and you do not age.
You gain immunity to poison damage. You are also immune to diseases, and the poisoned condition.
You gain immunity to Charmed, Frightened and Exhaustion conditions
You gain advantage to all saving throws against any effect that turns undead.
you gain darkvision to 60 feet, or if you already have darkvision, its range increases by 30 feet.
You can cast any known spell of 1st level at will

If you infused your Phylactery with your own flesh, you can cast on yourself disguise self spell at will and without concentration, but you make yourself look only exactly you looked like before the ritual. You cant cast this spell, if your Phylactery was destroyed.

Phylactery

Your phylactery is a special object which holds and safeguards a lich’s soul. In order to craft this wondrous item, you must spend 1d10+2 days and 6,000 gp. This cost covers the gems, precious metals, incense, and alchemical reagents needed in crafting the phylactery and brewing the Potion of Transformation.

Your phylactery can be a small jewel-encrusted box, a gemstone with pulsating runes, one of the other items mentioned above, or any other treasure a lich can dream up for their eternal existence.

After creating it, you may not travel to the outer planes as your soul is tethered by your phylactery.

Should you be reduced to zero hit points and die, your lich body crumbles to dust and, in 1d10 days, it reforms within 10 feet of your phylactery. Your phylactery must be intact in order for you to return. If your phylactery has been destroyed, you do not reform and you cannot be brought back only by a Wish Spell.

Similarly, a phylactery caught in an area of antimagic, such as one created by the Antimagic Field spell, cannot reform its lich. That lich is trapped inside their phylactery until it is removed or the field dissipates.

Your phylactery is tiny, has 40 hit points, it is immune to poison and psychic damage, and it has resistance to bludgeoning, piercing, and slashing damage from non-magical attacks.

Whenever the Phylactery is destroyed, you can survive for 1d10+10 days, before your lich body will be turned to ashes. In such way, you can only be ressurected by a Wish spell.

Lich Form and Phylactery

Changing creature type of a PC can be greatly unbalanced in some Campaigns. Speak with DM, will there be any problems with changing the type? Also, your DM can make couple of quests to achieve required ingredients for the Ritual, instead of a gold price.
Remember, Liches are dangerous, vile creatures. They are the strongest undead being, if someone will recognize you as a Lich, bewaree, as you will be hunted almost everyone, especially Paladin Orders, such as Silver Flame or others.
DM Note - You can ignore or change the effect, that restricts Lich Player traveling through other planes, if it is necessary for you campaign