Undead

Undying Will

At first level you gain the necrotic affinity as well as access to the following benefits. 

• Deathly Guise: You can use your bonus action to transform for a minute a number of times up to your proficiency bonus. Once per turn before making an attack you may attempt to unsettle your target with your haunting visage, the target must make a wisdom save against your Special DC granting you advantage on your first attack roll against them on a failure. While transformed via your deathly guise feature any damage you deal with an attack can be converted into necrotic damage and you may use your special modifier for attack and damage rolls.

• Reapers Hour: Once per turn whenever you kill a creature you may gain temporary hit points equal to your proficiency bonus, if the creature died as a result of taking necrotic damage you may instead regain hit points equal to half your proficiency bonus rounded up. While transformed into your deathly guise you instead gain twice your proficiency bonus in temporary hit points or your full proficiency bonus in hit points.

• Death's Cunning: You may use Wisdom in place of intelligence for calculating your special DC and attack bonus.

Not alive or dead...

At 6th level you gain the following features

• Inured to death: You gain resistance to necrotic damage and your hit point maximum cannot be reduced. While transformed into your deathly guise you gain DR equal to your constitution modifier and half your proficiency bonus.

• Bump in the night: You no longer need to sleep instead resting motionless but still fully conscious during rests, in addition you cannot be put to sleep by any means though you may still be knocked unconscious. You also gain darkvision out to a range of 60 feet and are unaffected by non-technique induced darkness.

But something in-between

At 11th level you are granted more benefits befitting your undead nature

• Walking Corpse:  Your deathly guise brings forth the fear of death within all things. At the end of each of your turns each creature of your choice within 60 feet of you that can see you must make a wisdom saving throw gaining one rank of frightened on a failed save. Creatures will remain frightened of you in this way until they succeed the saving throw at the end of your turn removing one rank of frightened on a success or gaining an addition rank of frightened on a failure.

• Just die already: Whenever you would take damage that reduces you to 0 hit points but does not outright kill you, you do not fall unconscious instead continuing to take turns as normal whilst also making death saves. You still suffer the effects of taking damage while at 0 hit points and if you would die you die. Your failed death saves are also reset whenever you succeed your third save, are stabilized, or healed. If you would be stabilized you fall unconscious.

• Spectral motion: You have advantage on checks and saves made to resist being grappled or restrained, in addition whenever you take damage you may expend a ferocity die and roll it reducing the damage taken by that much, then gaining DR equal to half the value rolled until the start of your next turn. While under the effects of your deathly guise you also  gain a flight speed equal to your walking speed, cannot fall, and cannot take fall damage. In addition whenever an effect would push you a number of feet you may choose to increase or decrease the amount of distance moved up to your movement speed without expending it.

Unrelenting Spirit:

At 18th level, your connection to death has reached its zenith, granting you the following abilities:

• Death's Avatar: While transformed via your Deathly Guise, you become immune to necrotic damage and gain resistance to all non-necrotic damage. Additionally, when you would be reduced to 0 hit points while transformed, you can instead drop to 1 hit point and immediately regain hit points equal to 5 times your proficiency bonus. This ability can only be used once per transformation.

• Soul Drain: Whenever you deal necrotic damage while in your Deathly Guise, you can choose to siphon the life force from your target. The target must succeed on a Constitution saving throw against your Special DC or have their maximum hit points reduced by an amount equal to the necrotic damage dealt. You regain hit points equal to the amount of hit points reduced. The reduction lasts until the target finishes a long rest.

• Spectral Army: As an action, you can summon spectral minions from the souls of the fallen. These spectral forms appear as ghostly figures within a 30-foot radius around you. You can summon a number of minions equal to half your proficiency bonus (rounded down). These minions are immune to all damage types except radiant and Haki Infused slashing, piercing, or bludgeoning. They act on your initiative and obey your mental commands. Each minion has hit points equal to your Constitution modifier + your proficiency bonus and deals 1d10 necrotic damage on a successful hit. This ability can be used once per long rest.