Necrolock

Your patron is the skull of a long lost powerful deity or entity from an older age or place. In exchange for teaching you the secrets of life and death, it wants you to gather its body parts scattered across the realms and resurrect its corporal body. Its parts can be disguised as various things such as an arm bone looking like a broom. the parts rattle and shift back to their original form when you bring the skull near. Only you can hear the skulls thoughts which are telepathically linked to you. The skull is a precious object and regards you as an ally. 

You gain powers over life and death eventually becoming a master over both. 

 

Expanded Spell List

The skull has taught you secrets to life and death from an expanded list of spells when you learn a warlock spell. The following spells are added to the warlock spell list for you.

Fiend Expanded Spells

Spell Level	Spells
1st	False Life, Healing Word
2nd	Blindness/Deafness, Aid
3rd	Animate Dead, Revivify
4th	Blight, Death Ward
5th	Contagion, Greater Restoration

Service to Life and Death

Starting at 3rd level, when you gain your pact boon, you gain additional bonuses.

For Pact of the Tome, Bestow Curse is added to your spells known and you can cast it at your level. 

For pact of the Blade, your weapon now deals an additional 1d6 necrotic damage, damage dealt is healed to you.

For pact of the Chain, your patron can be your familiar, and it is capable of possessing one unintelligent undead such as a skeleton or zombie permanently and gains the stat blocks to match and now takes turns independently, if its body is slain, the spirit returns to the skull and these feature can't be used again for a week. 

Lich

Starting at 6th level, you can sacrifice your health to fuel your spell casting in dire need. You take 20hp and gain 1 spell slot back. You can kill yourself this way.

Skeletal Form

Starting at 10th level, you can transmute yourself and shed your  flesh to become a skeleton. You become undead for damage purposes and no longer need to eat or breathe. Additionally you gain 2 ac due to your skeletal form being harder to hit. You may end this form at any time while conscious. 

While in this form you can convincingly play dead.  You cannot stay in this form for longer than 8 hours or you run the risk of dying or becoming undead permanently. if in this form for longer than 8 hours roll a 1d4 on an even you become a cursed undead, on an odd you die immediately no save. 

When you leave this form all previous injuries are healed and you temporarily gain a voracious appetite and thirst, which can be quenched with food and water, Additonaly you have other heightened biological senses and desires for 2 hours.

Once per long rest.

Life and Death Mastery

Starting at 14th level, you have attained mastery over life and death and can alter it as you choose once a week. You can cast True Resurrection or Power Word Kill once a week. True resurrection can only be cast during the day and power word kill can only be cast at night.