Order of the Bloodletter

The power of blood is intimately known by one type of creature above all others: vampires.  The sanguine drink grants direct boons to a vampire's supernatural abilities.  Generally speaking, a vampire is weaker when its supply of blood has been depleted.  However, some would argue that a bloodthirsty vampire is far more dangerous than a fully-fed one.  They are savage in their hunger and forgoe their usual cunning for a more brutal directness.  Blood hunters that follow the Order of the Bloodletter focus on channeling the more destructive nature of hemocraft.  They are able to devastate a creature's vitality at the cost of their own, refresh their own health with the expiration of another, and even affect the mending of wounds at their most powerful.

Rite of the Living Dead

When you join this order at 3rd level, you learn the Rite of the Living Dead as part of your Crimson Rite feature. When you activate the Rite of the Living Dead, the extra damage dealt by your rite is necrotic damage. 
    Blood Smite.  Whenever you hit with a weapon that has this Crimson Rite active on it, you can choose to sacrifice a portion of your lifeforce to perform a blood smite.  You can choose to sacrifice a number of hit dice equal to your proficiency bonus as a part of the same action and deal extra necrotic damage equal to the amount rolled.  Alternatively, you can choose to roll a number of hemocraft die equal to your proficiency bonus and take necrotic damage equal to the amount rolled to deal that much extra necrotic damage.  The damage to yourself cannot be reduced in any way.

Blighted Blood

Starting at 3rd level, creatures subjected to any of your blood curses receive only half the hit points for any healing they receive for the duration of that curse.  Creatures that are immune to necrotic damage are immune to this effect.

Additionally, you gain the Blood Curse of Bloated Agony for your Blood Maledict feature.  You can use this blood curse an additional number of times equal to your proficiency bonus.  This does not count against your number of blood curses known.

---

Blood Curse of Bloated Agony

As a bonus action, you curse a creature that you can see within 30 feet of you, causing its body to swell until the end of your next turn. For the duration, the creature has disadvantage on Strength checks and Dexterity checks, and takes 1d8 necrotic damage if it makes more than one attack during its turn.

Amplify. This curse lasts for 1 minute. The cursed creature can make a Constitution saving throw at the end of each of its turns, ending the curse on itself on a success.

Bloodless Resolve

Upon reaching 7th level, you cannot be reduced below 1 hit point by any of your Blood Hunter abilities.  However, if any of your Blood Hunter abilities would cause you to lose enough life to trigger this effect, then you have disadvantage on your next death saving throw.  This effect carries over to subsequent death saves.   I.E. If you would lose life on two separate instances from your Blood Hunter abilities and they would both put you below 1 hit point, then your next two death saves would be made with disadvantage.  Whenever you receive healing from a source, whether it be spell/magic item/ability/spending hit dice during a short rest/etc, you can remove one instance of disadvantage from the stack.  You remove any leftover disadvantage after finishing a long rest.

Brand of Decaying

Starting at 11th level, your Brand of Castigation binds the lifeforce of you and your quarry.  Whenever you take damage from using a Blood Hunter ability, the branded creature takes necrotic damage equal to half of the damage done to yourself (rounded down, minimum of 1).

Lifedrain

At 15th level, whenever a creature is reduced to 0 hit points by damage from one of your attacks or Blood Hunter abilities, you heal a number of hit points equal to a roll of your hemocraft die plus your Constitution modifier.

Blood Curse of Transfusion

Upon reaching 18th level, you’ve learned how to corrupt a creature's essence so that they can no longer receive vitality. You gain the Blood Curse of Transfusion for your Blood Maledict feature. This does not count against your number of blood curses known

---

Blood Curse of Transfusion

18th level, Order of the Bloodletter

As a reaction, you can corrupt one creature's anima that you can see within 60 feet of your location.  Whenever that creature would receive healing, in any form, they must succeed on a Constitution saving throw or instead take necrotic damage equal to the amount of hit points they would recover.  Their maximum hit points are lowered by an amount equal to the damage dealt. 

*The damage is based on the amount of healing they would receive prior to the effects of your Blighted Blood ability.

Amplify.  You are healed up to an amount equal to the damage dealt.  If this healing would go past your hit point maximum, you receive temporary hit points equal to the amount over your hit points maximum.