Lichborn

Your hidden magic bloodline has reanimated your corpse and pulled your soul back to the mortal coil

Cling to unlife

Starting at 1st level, your existence in a state of undeath makes you difficult to defeat. When you hit points fall to 0 you don't fall unconscious and can still take actions on your turn but as long as your hit points are below 1 you can't take bonus actions or reactions and must take death saving throws as normal.

Lich's Servant

At 1st level you can cast the find familiar spell without paying material costs. The familiar takes the form of a crawling claw. At 3rd level it's form changes to a skeleton. At 6th level it's form changes to an avatar of death.

Deaths Embrace

Starting at 6th level you gain immunity to necrotic damage

Deaths Embrace+

At 14th level your Deaths Embrace feature grows in power. You are now healed by Necrotic damage. Your growing ties to death weaken you to Radiant damage

Undead Horde

Starting at 14th level your connection with death grows stronger. You gain the ability to raise skeletons and zombies at will. You can cast the animate dead spell, but only as a fourth level spell. The undead created this way have immunity to turn undead and have 1d10 hit points and remain under your control until they are destroyed. There is no limit to the number of undead you can create in this way. Once you use this feature you can't again until you finish a short or long rest.

Phylactery

At 18th level you create rudimentary phylactery. Upon your death while your phylactery exists, your body will reform near your phylactery after 1d10 rounds of combat. Once it is used it will shatter into dust. A new phylactery can be created by sacrificing 20 undead creatures and a diamond worth 1000gp. You can only create 1 phylactery at any time