Oath of Blood

Using ancient and profane necromantic and sanguine rituals, an alchemist long ago was able to discover the secret of agelessness and greater power. This power came at the cost of a necessity of blood subsistence and a curse that was placed on all who performed these forbidden rites. 

In order to perform these rites, the user would have to contact a demon, and the demon would grant them power and agelessness at great cost to themselves. No longer could they stand the sun, no longer could food sustain them. The only thing that would feed their new and powerful bodies is blood, specifically the blood of humanoids. The rituals change everything about their body, leaving them no longer whatever they were, instead fortifying their power with supernatural blood that flows in their veins.

Despite the great cost of this, the tradition, rituals and such have been long passed down in secret, and out of this an order of knights has formed of those who hide their nature and feed off of the blood of humanoids to sustain their vicious immortality. These knights care not for the whims and wishes of others, rarely are they focused on anything but individual pleasure and power, partly as a result of the life they're forced to live, and partly because of the immortality and power granted by the rituals having a corrupting nature on the individual.

Corrupting Curse

When you take this Oath at 3rd level, you must perform a ritual, alchemical and demonic in nature that has been passed down through this order for generations. It involves using the blood of a humanoid to contact a powerful demon who bestows his "gift" upon you. Afterwards, you fall into immediate unconsciousness for at least 8 hours, during which time the blood in your body begins to change and alter with powerful magics, filling you with great physical and magical power, but also wracking your body with intense pain, as if you're being burned alive from the inside and changing the nature of your being. Once the transformation is over, the pain fades, leaving you with but a memory and great new powers, tempered by severe drawbacks.

Starting at 3rd level you gain the following abilities:

• Your mouth grows sharp teeth. Your bite is a natural weapon, which you can use to make unarmed strikes. If you hit with it, you deal piercing damage equal to 1d8 + your Strength modifier, instead of the normal bludgeoning damage for an unarmed strike.
• Once per short rest, when you hit with your bite attack, you can regain hitpoints equal to half the damage dealt + your constitution modifier. Hitpoints regained using this ability cannot exceed your hitpoint maximum.
• You gain a climbing speed equal to your walking speed.
• You replace the damage type of your spells that deal radiant damage and your smites with necrotic damage. This includes your divine smite and later on, improved divine smite. Your divine smite no longer does an additional d8 of damage to undead and fiends and instead does an additional d8 to humanoids and celestials to a maximum of 6d8.

Starting at 3rd level you suffer the following drawbacks, as a result of your curse:

• You take acid damage equal to your total character level if you end your turn in running water.
• You take radiant damage equal to your total character level if you end your turn in direct sunlight.
• While in direct sunlight, you have disadvantage on attack rolls and ability checks.
• If you're reduced to 0 hitpoints by radiant damage or by a piercing weapon, your body turns to ash immediately and you die.
• Your lay on hands feature can now only target yourself.

Oath Spells

You gain oath spells at the paladin levels listed in the Oath of Conquest Spells table. See the Sacred Oath class feature for how oath spells work.

Oath of Conquest Spells

Channel Divinity

When you take this oath at 3rd level, your smites deal necrotic damage instead of radiant and you gain the following two Channel Divinity options. See the Sacred Oath class feature for how Channel Divinity works.

Fearful Presence. You can use your Channel Divinity to exude a terrifying presence. As an action, you force each creature of your choice that you can see within 30 feet of you to make a Wisdom saving throw. On a failed save, a creature becomes frightened of you for 1 minute. The frightened creature can repeat this saving throw at the end of each of its turns, ending the effect on itself on a success

Cursed Weapon. As an action, you can imbue one weapon that you are holding with necromantic energy, using your Channel Divinity. For 1 minute, you add your Charisma modifier to damage rolls made with that weapon (with a minimum bonus of +1). The weapon also emits dim light in a 20-foot radius. If the weapon is not already magical, it becomes magical for the Duration. In addition, any damage you deal with this weapon becomes necrotic. 

You can end this effect on your turn as part of any other action. If you are no longer holding or carrying this weapon, or if you fall unconscious, this effect ends.

Bloodthirsty Aura

Starting at 7th level, you constantly emanate a bloodthirsty aura while you’re not incapacitated. The aura extends 10 feet from you in every direction, but not through total cover. 

Whenever a friendly creature in the aura reduces a creature to 0 hitpoints, they gain temporary hitpoints equal to your charisma modifier + half your paladin level.

The range of this aura increases to 30 feet when you reach 18th level in this class.

Vampiric Nature

Starting at 15th level, the corrupting nature of your curse changes your very body irrevocably. You cease to age completely. You cannot be aged magically. You do not need to breathe, and you do not need food or water. 

In addition You gain immunity to poison damage and the poisoned condition. You also gain resistance to necrotic damage. For the purposes of spells and abilities such as the detect evil and good spell or the Paladin's divine sense, you're considered to be undead.

Lord of the Night

At 20th level, you gain the ability to harness all the powers of the night. As an action, you can magically become an avatar of darkness, gaining the following benefits for 1 minute:

• If you take the Attack action on your turn, you can cast a paladin spell that has a casting time of 1 action using your bonus action instead.
• You gain advantage on death saving throws, and on strength and dexterity saving throws, ability checks and attack rolls that use strength or dexterity.
• At the start of each of your turns, you regain 10 hp if you have at least 1 hit point and aren't in running water or sunlight.

Once you use this feature, you can’t use it again until you finish a long rest.