Blood Resonance Optional Rules
Source: https://vamp.bynightstudios.com/vampire/library/bloodresonanceoptionalrules
You are what you eat, as the adage goes. While the Ventrue are known for their strict feeding preferences, vampires of all clans tend to develop their own personal tastes with regard to whom they feed upon. These preferences may be for deeply personal reasons, such as a religious belief, a set of values, or a superstition developed over years. Some vampires insist they can taste the emotions of their victims, and that certain sentiments enhance the experience of feeding. The emotional state of a feeding vessel, as it applies to her blood is her Resonance; a function of her state of mind and her environment.
NOTE: Although this section contains some nods to the tabletop role-playing game Vampire: The Masquerade 5th Edition ("V5"), nothing in this book affects the V5 continuity.
Humors
The concept of humors originated in Ancient Greece and spread throughout Europe and the Middle East. It remained an influential model until the 16th century when it gave way to modern anatomy. As it was the dominant medical paradigm throughout most of recorded history, in spite of science having advanced beyond its simple taxonomy, many vampires use humorism to explain blood Resonance.
Humorism states that there are 4 fluids that make up the human anatomy. Imbalances in these humors cause an array of conditions, such as depression, lethargy, aggression, or manic episodes. Medicine, therefore, sought to restore the balance between humors through a variety of means. Vampires understand that by feeding from vessels with differing levels of the humors, one can temporarily alter one's own emotional state or physiology. Further still, it has become known that certain disciplines function better with an abundance of certain humors.
The Four Humors
Vampires who consume blood with an excess of a specific humor experience specific types of emotion. While these emotions generally have no mechanical effect, they should be used as tools by players and Storytellers to enhance the role-playing experience. How long the emotional experience caused by a specific humor affects the vampire that ingested that blood is at the discretion of the Storyteller and the player. The four humors are:
Choleric
Yellow bile is the choleric humor. Vampires who consume blood with an excess of this humor experience sensations of anger, violence, passion, envy, or aggression.
Melancholic
Black bile is the melancholic humor. Vampires who consume blood with an excess of this humor experience sensations of sadness, fear, awareness, or melancholy.
Phlegmatic
Phlegm gives the phlegmatic humor. Vampires who consume blood with an excess of this humor experience sensations of apathy, calm, lethargy, or indifference.
Sanguine
Blood is the sanguine humor. Vampires who consume blood with an excess of this humor experience sensations of enthusiasm, vitality, excitement, or joy.
System Rules
Dyscrasia
A Dyscrasia is a state that results from a significant deficiency or excess of one or more of the four humors. Traditionally, this is caused by a biological dysfunction. For vampires, a Dyscrasia is a strong emotional state in a feeding vessel. If the vessel's blood is consumed while the vessel has a Dyscrasia, the condition will temporarily affect the vampire, manifesting as an unconscious process. While all vampires are aware of the humors, the workings of Dyscrasias are far from an exact science and, according to some, are merely a psycho-somatic response.
Tapping a Dyscrasia
When a vampire feeds from a vessel with a Dyscrasia, the Storyteller will provide the player with a card that she can use at any time, including outside her character's initiative or during Celerity rounds. Using this card gives the character a one-time benefit depending on the type of Dyscrasia. Unless otherwise stated, this benefit lasts for only a single challenge. A vampire can only benefit from a single Dyscrasia. If the character later feeds from another human or animal, the player must forfeit her card as the blood in her character's system is diluted but she may receive a new Dyscrasia if the vessel has one, resulting in the player receiving a new card. A Dyscrasia must be used before the end of the night or its benefits will expire.
Source Book: MET - VTM - V2 (2021)