Oath of the Deathknight

A paladin that has devoted themself to the Ideal of bringing death to the unworthy

Profanity

At Level 3, when the Paladin foreswears ever taking an oath like other paladins. 
This grants the several profanities(Charisma+1) that can be activated/Deactivated as a Bonus action. 
To take these profanities into the paladin's soul means that he will not be granted any spells for being a Death Knight, nor will he ever be able to Channel Divinity.
At level 3 the paladin may have 1 Profanity active, this increases by one at level 5 to a total of 2, at level 12 to a total of 3 and at level 18 to a total of 4.
Should the Paladin activate more a Profanity when they are at the maximum allowed, they will choose one profanity that will deactivate immediately.
At level 10, the Paladin gains Resistance to Necrotic damage while having at least 1 Profanity active

If more than 1 profanity effect is active at the end of the Paladins turn in combat, they must make a DC 15 Constitution Saving throw, if this fail, a random Profanity will deactivate.
Should the paladin fall unconscious(though not by natural sleep), all the profanities will deactivate.

The list of Profanities that can be chosen from is:

Aura Of The Damned
Any enemy creature within 20 feet must make a Constitution saving throw or be at disadvantage on attack rolls made against you

Glamour of Death
You can add your Charisma modifier to all saving throws.

Armour of the Grave
Gain +2 AC against enemies that are making melee attacks against you

On a Pale Horse
You summon a ghostly looking horse beneath you, increasing your speed by 10.

Soulflay
A creature you choose within 30 feet of you have disadvantage on a single saving throw of your choice.

Reaving the souls
The weapon(s) you hold becomes bathed in the essence of your aura. The weapon must be a bound weapon(see below). On a successful attack add an additional 1d4 of necrotic damage. Increases to 1d6 at level 6, and 1d8 at level 10.

Terrorize
If a creature moves to within 30 feet of you, you can use your reaction and the creature must succeed on a Wisdom saving throw or become frightened of you for 1 minute. The DC is equal to 8 + your Strength modifier + your proficiency bonus. Whether successful or not, a creature cannot be targeted by this ability again until you finish a long rest.

 

Bound Weapon

At level 3, you learn a ritual that creates a magical, living bond between yourself and one weapon per casting. You perform the ritual over the course of 1 hour, which can be done during a short rest. The weapon must be within your reach throughout the ritual, at the conclusion of which you touch the weapon and forge the bond. Once you have bonded a weapon to yourself, you can't be disarmed of that weapon unless you are incapacitated. You can summon that weapon as a bonus action on your turn, causing it to instantly materialize in your hand unless it is held by a greater power(Gods, etc). In addition, you may also absorb its physical form within your very being, which may act as an effective storage place. You can have up to two bonded weapons but can summon only one at a time with your bonus action. If you attempt to bond with a third weapon, you automatically break the bond with one of the other two. You gain a +1 bonus to all attack and damage rolls with your bound weapon.

Death's Grace

As death stalks the lands, they leave no traces of their passing, the paladin is not quite there yet, but they hover a few inches from the ground. The paladin does not trigger pressure plates or the like, and they can cross liquid surfaces if they are still; furthermore, they descend to the ground harmlessly as if under the effect of the 'Feather Fall' spell should there be more than a few inches down.

Siphoning Strikes

At 7th level, the paladin learns to control the balance of life and death within themself. When they reduce a creature to 0 hit points, they gain temporary hit points equal to their Charisma modifier. At the end of combat, these temporary hit points are turned into healing.

Shadow Meld

At 7th level, as an action or bonus action you may teleport to a point you can see within 60 feet if you and that point are both in darkness. You may also take one other creature with you. If the creature is not willing, it must succeed on a Dexterity saving throw to evade you. DC being 8 + your Constitution modifier + your proficiency bonus

Death's Embrace

At 15th level, the Deathknight gains resistance to non-magical slashing, piercing, and bludgeoning damage. In addition, the Death Knight takes on some of the traits of Death itself:

• You no longer age, and are immune to all aging effects
• You no longer require sleep or food, and can achieve Long Rest by doing four hours of light activity.
• Your hit point maximum cannot be reduced
• You gain resistance to Necrotic Damage

Lord of Death

At 20th level, the paladin can, as an action, surround himself or herself with an aura of death that lasts for 1 minute. Any creatures the paladin chooses which start their turn within the 30-ft. aura is afflicted with level 3 Exhaustion, granting disadvantage on ability checks, attack rolls,  and saving throws and their movement speed is halved. If a creature thus afflicted leaves the aura, the exhaustion fades at 1 level per turn spent entirely outside the aura. Successful attacks against creatures affected by the aura deal an additional 3d8 + Charisma Modifier necrotic damage, healing the attacker for half, rounded down.

Creatures that are immune to exhaustion do not suffer from the exhaustion effects but do suffer from the bonus necrotic damage.

After activating the aura, the paladin can’t do so again until he or she finishes a long rest.