Oath of Bone

Paladins of the Oath of Bone, sometimes known as "bone collectors", are paladins tied to a powerful undead extraplanar entity: Oogdaroog, the Bone Collector. Oogdaroog resides in his demi-plane, the endless boneyard, while not being a true deity, he is still worshiped by the more intelligent undead and even mortals who seek to gain his favor. Unlike other entities that might share their power with mortals, Oogdaroog only shares this power with clerics and paladins, because they possess the two things he needs devotion and conviction. The clerics that serve Oogdaroog ensure he has worshipers, ensuring his power remains or even grows as well as finding new paladins to bestow his power to. Most paladins who take on the Oath of Bone, rarely do so out of their own volition but are saught out by Oogdaroog's clerics. The oath that these paladins swear can be whatever they want so long as their conviction to following that oath is firm. Because conviction is the thing, Oogdaroog desires from his paladins because if they have conviction, they will carry out his desire to gather bones. When a paladin takes the Oath of Bone, they receive a magical tower shield made of bones, the Oathbone Shield, upon that shield is inscribed the oath they took in every language, even dead ones. But on the inside of the shield, there is a message regardless of what oath they may have made that only they can see "Never forget who you truly serve, and never forget what your duty is". The shield is a physical manifestation of the paladin's conviction and is tied to their very soul, should the paladin lose his conviction entirely, he will die, and his soul will be destroyed. Because Oogdaroog can't share his power with living creatures, he instead puts those willing to become his paladins in a state of constant flux between living and undead. While undead, their smell, taste, and touch are a bit muted, and they also stop aging. People who would seek out Oogdaroog for assistance are usually ones that have a cause they desperately wish to fight for but don't have the means to do so or, in some rarer cases, revenants seeking aid in fulfilling their unfinished business.

Death's Embrace

At Lv. 3 you gain Death's Embrace: You attain a new state of being, you are both living and undead, existing in a state of flux between the two. As a living creature, you gain immunity to holy spells and 50% resistance to necrotic and poison damage. As an undead you gain immunity to necrotic and poison damage but take x2 damage from radiant damage, holy spells, and silver weapons, you suffer a -5 on any perception check that relies on taste, touch and smell, you also don't require air, food, water or sleep. To determine whether you are living or undead for a certain interaction or effect, roll a d6: On a roll of 1 or 6, you are treated as living, and on a roll of 2,3,4 or 5 you are treated as undead. You can't regain HP except with "Draining Touch" or finishing a long rest. This means that healing potions, spells, and any other healing effects do not restore your HP while you are treated as a living creature, while you are treated as an undead creature healing spells damage you instead. 

Oath of Bone

At Lv. 3 you gain Oath of Bone: You can make any oath that you want and when you take that oath you get the Oathbone Shield, a magical tower shield, made entirely from bones, that is inscribed with your oath in every language, even dead ones. The shield is indestructible and magically tied to you. If it gets more than 100ft from you, it will teleport to you within 10 minutes. But if your conviction wavers, the shield will begin to crack, and if you lose your conviction entirely, the shield will shatter, and you will die, your soul being destroyed. You can change your oath by meditating for 7 days and offering at least two full, humanoid skeletons to Oogdaroog. You gain no AC bonus form wearing light or medium armor. The Oathbone Shield gives you a +2 AC, and as a bonus action, you can hunker down, giving yourself half cover until you move. You can attack with the Oathbone shield dealing 1d8 bludgeoning damage or 1d10 if you have no weapon in your other hand. Your "Devine Smite" damage is changed form radiant to acid and you gain several Oath spells.

Oath of Bone Spells

Draining Touch

At Lv. 3 you gain Draining Touch: This ability replaces your "Lay on Hands". As either a standard or bonus action, touch 1 creature and drain 1d8 HP form it and restore an equal amount to yourself, the recovered HP can't exceed your max HP. You can use this ability a number of times equal to your CHA modifier + 1, before needing to complete a long rest. You gain 1 additional die to your draining touch at lv7, 11, 15, and 19. At lv6 you can drain spell slots from creatures instead of HP(your target mus have at least 2 spell slots), you use the same die as for the HP drain but you regain 1 spell slot for every 2 spell slots you drain(going from lowest to highest). If you drain a lv6 or higher spell slot you regain 3 of your spell slots, the spell slots you regain can't exceed your max spell slots. You can't drain used spell slots, if a creature has used all of its spell slots, you can't drain spell slots from it. 

Channel Divinity : Life Drain

At lv3 you gain 2 options for Channel Divinity
Smiting Drain: You can expend 1 use of your "Draining Touch" when you use your smite and heal yourself equal to the amount of damage you deal with your smite.
Heavy Drain: You can use your "Draining Touch" 1 additional time on the same target, this does not count towards your maximum uses. At lv13 you can use it 2 additional times, for a total of 3 consecutive "Draining Touch".

Shield Combat

At Lv. 7 you gain Shield Combat: Increase your Oathbone Shield damage die to a d10 and d12 when you have no weapon in your other hand. Whenever you attack with your shield as a bonus action you can shove the creature. As a standard action, you can charge 1 target with your shield, you don't trigger attacks of opportunity when charging towards the target and deal an additional d4 bludgeoning damage for every 5ft passed. You can only shield charge if you have no weapon in your other hand. Whenever you score a critical hit with your Oathbone Shield the target becomes stunned for 1 round.

Decay

At Lv. 7 you gain Decay: You can channel pure negative energy to your hands, dissolving any non-organic or dead material, the only exception being stone. The area of effect is limited to your hands. For example, when you touch a piece of metal you will dissolve it as if acid was poured over it. Or you trace your finger across a door, melting a shape into the door. The dissolving effect is not instantaneous but requires you press your hand into the object for en extended period of time, the thicker and sturdier the object, the more time it will require. This ability only affects inanimate objects.

e.g. It would take a couple of seconds to dissolve a thin sheet of paper, several minutes to dissolve full plate armor and several hours to dissolve a 5ft thick gate.

Caustic Breath

At Lv. 7 you gain Caustic Breath: As a standard or bonus action, you can breathe a stream of acid, in a straight line with a range of your movement speed, dealing 1d6 acid damage * 1/4 your paladin lv. You can expend all your spell slots(min 5) to make the ability deal 1d6 acid damage * your paladin lv. You can use this ability once per long rest. You gain an additional use at 13th and 17th lv. 

Grave Drain

At Lv. 15 you gain Grave Drain: As a standard action, you can make skeletal hands erupt from the ground grabbing and restraining 1 creature within 30ft of you. The creature is restrained for 1 turn and pushed back to last in the initiative order for that round if it hasn't taken its turn yet. If an attack is made against that creature it is released immediately and can take its turn as normal. You can use "Draining Touch" through the skeletal hands that are holding it as if you were touching it yourself, using "Draining Touch" doesn't release the target from the skeletal hands. You can use this ability 3 times per short rest. 

Corrosive Strike

At Lv. 15 you gain Corrosive Strike: Whenever you inflict acid damage to an opponent, with your Oathbone Shield reduce its AC by 1. The maximum reduction you can inflict to a creature is 5, but if its AC is >20 then the maximum reduction is 7.

Malignant Aura

At Lv. 15 you gain Malignant Aura: Whenever a creature within 10ft of you takes acid damage, it must make a WIS saving throw with a DC of 18 or be frightened for 2d6 rounds. As long as a frightened creature is within 10ft you, it takes 1d12 necrotic damage every round. At lv18 the range is increased to 30ft.

Oogdaroog's Harvest

At Lv. 20 you gain Oogdaroog's Harvest:  As a standard action target 1 living or undead creature, that is at 1/10 or lower of its max HP. It must make a DC 20 CON save if it fails it has all its bones stolen and teleported to Oogdaroog's demi-plane. If it doesn't have bones, like an octopus, it's skin is dissolved. The creature is instantly killed. You can target 1 creature that doesn't meat the HP requirement, and use this ability on it. But if you do, you can't use this ability for the next 24 hours. This ability automatically fails if the target has no bones and no skin.