Blood System (5e variant rule)
Blood System[edit]
In the Chainsaw Man universe, blood is not only a source of power but an important life force, especially for hybrids, devils, and fiends. This system aims to bring a realistic and immersive blood mechanic to life, allowing players and DMs to accurately value the cost of violence, regeneration, and survival.
- Blood System
The amount of blood points a creature has is equal to (10 × Constitution score) + (2 x their character level or Challenge Rating). Blood points function as a secondary resource that represents the total blood volume within a creature’s body. Only slashing and piercing damage, or the bleeding condition, can cause a loss of blood points.
A creature cannot regain hit points if it is at 0 blood points. When a creature's blood points are reduced to 0, they die instantly. However, most creatures begin to suffer biological consequences long before reaching 0.
When a creature’s current BP falls below these thresholds, they suffer the following effects:
When a creature’s current BP falls below these thresholds, they suffer the following effects:
- At or below ½ of max BP. The creature gains 1 level of exhaustion.
- At or below ¼ of max BP. The creature gains 1 additional level of exhaustion and suffers disadvantage on all Strength, Dexterity, and Constitution ability checks and saving throws.
- At or below ⅙ of max BP. The creature gains 1 additional level of exhaustion and must succeed on a DC 10 Constitution saving throw or fall unconscious at the start of each of their turns. The DC increases by 2 for every successful save at the start of each of their turns.
- At or below ⅛ of max BP. The creature gains 2 additional levels of exhaustion, suffers disadvantage on all attack rolls, and falls unconscious immediately if their BP reaches 0. They must make death saving throws at the start of each turn.
- At 0 BP. The creature dies instantly.
These effects apply to humans, fiends, and hybrids. While their origins or nature may differ, they all inhabit human bodies and are therefore subject to mortal biology.
Hybrids. Upon activating their transformation as a bonus action, the hybrid spends blood points equal to Constitution score. A hybrid who is killed may still be revived if their trigger is pulled, as if activating their transformation. Doing so restores half of their hit point maximum. However, a hybrid cannot transform or be revived this way if they do not possess the required blood points. A creature must use either their bonus action or reaction to pull the trigger.
How to gain blood points. If you are a fiend, devil, or hybrid, you regain blood points by drawing blood from others. Whenever you deal slashing or piercing damage to a creature, you regain blood points equal to one-third of the damage dealt (rounded down). The blood is absorbed passively through contact, ingestion, or devil anatomy.
How to regain blood points. Humans cannot regenerate blood passively. They regain all blood points upon completing a long rest, provided they have access to food, water, and have not suffered internal bleeding or limb loss. If a human has lost blood points, they may also regain them through transfusions, or consumables such as blood packs.
Bleeding. When under the effects of the bleeding condition, a creature loses blood points equal to ⅓ of the damage taken per instance of slashing or piercing damage. This loss is in addition to any regular damage suffered and continues until the bleeding is stopped.
Limb System. When a limb is severed or destroyed, the creature loses blood points equal to that limb’s current hit points until the limb is restored to its full hit points.
Blood Types. At character creation, roll 1d8 to determine your blood type. This may affect compatibility for transfusions. The table below determines your blood type:
| Blood Type Roll | Blood Type |
|---|---|
| 1 | O- |
| 2 | O+ |
| 3 | A- |
| 4 | A+ |
| 5 | B- |
| 6 | B+ |
| 7 | AB- |
| 8 | AB+ |
Some items such as blood packs may only work on specific blood types unless treated or magically modified. Attempting an incompatible transfusion may cause damage, rejection, or further blood loss.
