Boon of the Blood Caster

Drawing Blood

Upon first gaining the Boon of the Blood caster, you learn to draw out and manipulate the blood in your body. As an action, you can use a ritual dagger cut into your body, drawing out your blood and providing one Blood Point.

Each time you perform this action your constitution drops by 2, and decreases your maximum health equal to your level. The decrease in constitution reflects in any correponding checks or saving throws. You can use this blood point as part of the draw , or hold it in reserve using at described below. Any accumulated blood points fade during a long rest.

Constituion lost in this manner cannot be recovered magically, instead only being returned by 1 point on a short rest, or 4 points on a long rest. Max HP also cannot be regained magically, and only recovers on a short rest(dependant on recovered constituion)

Blood Focus

Using the blood drawn from your body, you can focus it to gain a specific temporary benefit. As an action you can spend 1 blood point to gain any of the following benefits for 10 minutes.

• Darkvision
• Advantage on one type of saving throw(declared when blood spent)
• Proficiency with a tool
• Keen vision and smell
• Proficiency with 1 skill(declared when blood spent)
• Understand and speak 1 language

As a more difficult ability, you can spend 2 blood points to gain any of the following beneifts for 10 minutes

• Immunity to being put to sleep
• Weapon or Armor Proficiency
• Resistance to 1 damage type(declared when blood spent)
• Breath Weapon
• Blood Resevoir(1 use of Relentless Endurance)

Magical Blood Use

With continued use of your blood, you begin to unlock its arcane potential. At 3rd level, in addition to the mundane uses as a Blood Focus, you can expend blood points similar to sorcerer points. Blood points spent in this manner regain spell slots equal to the number of points spent, not to exceed 5th level spells.

Additionally, choose 1 of sorcerer Meta Magic features, which you can activate by spending 2 accumulated blood points when casting a spell. You can choose an additional Meta Magic at 9th level.

If your current class does not have spell casting, choose 1 spell from the sorcerer spell list upon gaining this feature. You can change the spell each time you level up.

Faster Blood Draw

At 5th level, you no longer require the ritual dagger and are able to more quickly draw and use your blood, choosing between an action or bonus action each time, or using both to draw 2 blood points on your turn.

More Efficient Blood Draw

At 7th level you are able to gain blood without inflicting as severe of a wound. You now only lose 1 Constituion point and your max health decreases by half your level(rounded down).

Blood Recovery

Why let freshly spilled blood go to waste? At 11th level you can now use your reaction to gather freshly spilled blood from any successful melee strike within 15 feet of you(including against yourself or allies).

This reaction excludes any creatures that does not contain blood, such as constructs, or creatures that do not contain fresh blood, such as undead.

When gathered this way the blood draw does not negatively impact Constituion or Max health, but any blood gathered fades on a short rest.

How to be Implemented

This can be granted as a direct and very powerful boon, with each new ability being gained as you gain levels or as successive boons. This can also be an alternative race - replacing all racial features except for ASI. Lastly knowledge of this Boon could be taught by a powerful Devil or Hag, with progress provided in exchange for a deal appropriate to the giver's desires.