You’ve made a pact with a soul who has been lost in a sea of blood from an unknown plane for as long as the multiverse has existed. They allow you to draw on their strength in blood magic in exchange for using you as their vessel. They care not what you do since they just want to see a world that is not an ocean of blood. This lost soul also grants you the ability to not age so that they can see people change and civilizations evolve.

Expanded Spell List

Spell Level	Spells
1	Dissonant Whispers,False Life
2	Phantasmal Force, Scorching Ray
3	Lightning Bolt, Life Transference
4	Death Ward, Phantasmal Killer
5	Insect Plague, Contagion

Demonic Blood

At 1st level you bond with this patron, giving you new abilities. You gain new abilities that you can do at the cost of blood points. If a blood action needs an attack roll, you use your spell cast modifier. You gain blood points equal to your spell cast modifier (min of 1). You have the ability to spend your own blood for these attacks once you run out of your patron’s blood. As an action you can spend one hit die worth of HP, to gain another Blood Point. You regain all blood points after a short/long rest. (Any attack that uses a save uses your spell save DC)

Upon making the pact with this patron you allow into your body and into your bloodstream. Doing so gives you an immunity to necrotic damage. You also now read as a demon or fiend.

Blood Actions

Action	Minimum Blood Point(BP) Cost
Sanguine Spear	2
Life Drain	2
Sanguine Spikes	2
Blood Leap	4
Spike Explosions	4
Total Control	6

Sanguine Spear:

A spear made of your blood shoots from your hand. When it hits the target, they take 1d8 piercing damage. As the spear gets absorbed by the target’s body they must make a CON save. On a failed save, the target takes 1d8 necrotic for each blood point spent on this action.

Life Drain:

You focus on your target dealing 1d6 necrotic damage per Blood Point cost. You heal an amount equal to damage dealt. You can also give the healing to an ally.

Sanguine Spikes

For each blood point spent on this action, you can conjure up small spiked objects that you can place within 15ft of you. These spikes use the caltrop rules.

• They take up a 5ft square. Any creature that enters the area must succeed on a DC 15 Dexterity saving throw or stop moving this turn and take 1 piercing damage. Taking this damage reduces the creature's walking speed by 10 feet until the creature regains at least 1 hit point. A creature moving through the area at half speed doesn't need to make the save.

Blood Leap:

You can teleport to an unoccupied space that you can see within 30ft. When you teleport to your space, any creature within 5ft of your original place must make a CON save. On a failed save, the creatures take 1d6 necrotic damage.

Spike Explosion

Spikes shoot out from all over your body. Every creature in a 10ft radius takes 1d8 piercing damage on a failed DEX save.

Total Control

You look deeply into your target and take control of their body. Tthe target must make a WIS save and if they fail, then you can control them on their next turn(unless you are incapacitated by that point).

Blood Transfer

Upon reaching 6th level, when an enemy drops you to 0 hit points, your patron will reach out and connect you to them. He deals 1d8 + CON necrotic damage to the target and you heal an equal amount of health. You can do this again after a long rest

Sanguine Wave

At 10th level, your patron teaches you Destructive Wave. It counts as a warlock spell for you, but it doesn't count against the number of spells you know. You can also cast it once without using a spell slot, and you regain the ability to do so when you finish a long rest.

Blood Keeper's Avatar

At 14th level, your patron bestows upon you their body. You gain the ability to take the form of the Blood Keeper themself. This form lasts for 1 hour, or until you revert back to your regular form. You use the patron’s STR, DEX, CON scores, but your CHA, WIS, and INT scores.

The Blood Keeper

Large elemental, neutral

Armor Class 14 (natural armor)

Hit Points 114 (12d10 + 48)

Speed 30 ft., swim 90 ft.

When you take the Blood Keeper's form you gain the Strength, Dexterity, and Constitution of The Blood Keeper and keep your Wisdom, Intelligence, and Charisma. 

STR	DEX	CON
18 (+4)	14 (+2)	18 (+4)

Damage Resistances: acid; bludgeoning, piercing, and slashing from non-magical attacks

Damage Immunities: poison, necrotic

Condition Immunities exhaustion, grappled, paralyzed, petrified, poisoned, prone, restrained, unconscious

Senses darkvision 60 ft., passive Perception 10

Languages: same as you, infernal

Challenge 5 (1,800 XP)

Blood Form. The elemental can enter a hostile creature's space and stop there. It can move through a space as narrow as 1 inch wide without squeezing.

Freeze. If the elemental takes cold damage, it partially freezes; its speed is reduced by 20 feet until the end of its next turn.

Actions

Multiattack The elemental makes two slam attacks.

Slam. Melee Weapon Attack: +7 to hit, reach 5 ft., one target. Hit: 13 (2d8 + 4) bludgeoning damage.

Whelm (Recharge 4–6). Each creature in the Keeper’s space must make a DC 15 Strength saving throw. On a failure, a target takes 13 (2d8 + 4) bludgeoning damage. If it is Large or smaller, it is also grappled (escape DC 14). Until this grapple ends, the target is restrained and unable to breathe unless it can breathe water. If the saving throw is successful, the target is pushed out of the Keeper's space.

The Keeper can grapple one Large creature or up to two Medium or smaller creatures at one time. At the start of each of the elemental's turns, each target grappled by it takes 13 (2d8 + 4) bludgeoning damage. A creature within 5 feet of the elemental can pull a creature or object out of them by taking an action to make a DC 14 Strength and succeeding.