Connard, The Unstable lich

Indestructible Life EX On your turn, you can use a bonus action to regain hit points equal to 2d8 + 16. Additionally, if you put a severed body part of yours back in place when you use this feature, the part is reattached.

Horrifying Visage Each non-undead creature of the creature's choice within range must make a DC 16 Wisdom saving throw or be frightened for 1 minute.

Pact Of The Blade as a free action, you can either summon or dispel the Axe Of Conquest

Pact Of The Chain You have an Imp familiar that can be summoned with 25 hitpoints

Undead Invocations Once a warlock in life, the invocations seem to have carried over, some of which are a little stronger than before.
Agonizing Blast: When you cast Eldritch Blast, add your Charisma modifier x2 (minimum of 2) to the damage it deals on a hit.
Armor Of Shadows: You can cast Mage Armor on yourself at will, without expending a spell slot or material components.
Bewitching Whispers: You can cast Compulsion once using a warlock spell slot. You can't do so again until you finish a long rest.
Cloak Of Flies:  As a bonus action, you can surround yourself with a magical aura that looks like buzzing flies. The aura extends 5 feet from you in every direction, but not through total cover. It lasts until you're incapacitated or you dismiss it as a bonus action. The aura grants you advantage on Charisma (Intimidation) checks but disadvantage on all other Charisma checks. Any other creature that starts its turn in the aura takes poison damage equal to your Charisma modifier x2 (minimum of 2 damage). Once you use this invocation, you can’t use it again until you finish a short or long rest.
Life Drinker: When you hit a creature with your pact weapon, the creature takes extra necrotic damage equal to your Charisma modifier x2 (minimum 2).
Thirsting Blade: You can attack with your pact weapon twice, instead of once, whenever you take the Attack action on your turn.
Sculptor Of Flesh: You can cast Polymorph once using a warlock spell slot. You can't do so again until you finish a long rest.

Legendary Resistance(once per day) If you were to fail a save, you can instead choose to succeed it.

Spellcasting. Connard is a 16th-level spellcaster. Its spellcasting ability is Charisma (spell save DC 18, +10 to hit with spell attacks). Connard has the following spells prepared:
Cantrips (at will): Ray Of Frost, Poison Spray, Chill Touch, Eldritch Blast, Mage Hand, Fire Bolt, Vicious Mockery, Spare The Dying
1st level: False life, Ray Of Sickness, Hellish Rebuke, Expeditious Retreat
2nd level: Blindness/Deafness, Silence, Shatter, Ray Of Enfeeblement
3rd level: Feign Death, Speak With Dead, Vampiric touch, Counterspell
4th level: Aura Of Life, Death Ward, Banishment, Blight, Dimension Door
5th level(6 slots): Contagion, Legend Lore, Scrying
6th level(once per day): Circle of Death
7th level(once per day): Finger Of Death
8th level(once per day): Dominate Monster

Axe Of Conquest Charges The Axe Of Conquest has 1d8+2 charges at the start of any day. You can use one charge per spell slot (say it's a 5th level spell, it would take 5 charges. Alternatively, you can use 5 charges to use a normally 1st level spell at 5th level) to use any of the following:
Searing Smite, Wrathful Smite, Blinding Smite, Staggering Smite, Banishing Smite

Turn Resistance. The lich has advantage on saving throws against any effect that turns undead.

Rejuvenation. If it has a phylactery, a destroyed lich gains a new body in 1d10 days, regaining all its hit points and becoming active again. The new body appears within 5 feet of the phylactery.

Multiattack When you take the attack action, you can choose to make 2 attacks with the Axe Of Conquest

Axe Of Conquest. Melee Weapon Attack: +10 to hit, reach 10 ft., 1 target. Hit: # (4d6 + 6) slashing damage + 12 necrotic damage

Fight Back When attacked within range of your melee attack, you can make a melee attack with the Axe Of Conquest, given it is summoned.

Defy Death EX When you are brought below 0 hit points, you can instead be brought to 1d8+6 hit points. This can only be used once per day.