Blood

"Blood is life, lackbrain. Why do you think we eat it? It's what keeps you going, makes you warm, makes you hard, makes you other than dead."

- Spike to Xander Harris on the nature of blood



Blood was a specialized bodily fluid that delivered necessary substances to a body's cells – such as nutrients and oxygen – and transported waste products away from those same cells. It was found in most beings, including humans.

Vampires were well known to feed on the blood of mammals, and it was a common ingredient in numerous magic spells and rituals. The blood of Mohra demons possessed regenerative properties.

The consumption of blood could provide details about the person. Glorificus instantly determined that Tara Maclay wasn't the Key by licking her bloody hand and Spike confirmed that Cordelia Chase was not a demon by drinking blood.

Uses in magic

 * A central ingredient in resurrection spells
 * As the human form of The Key, Dawn Summers' blood possessed the power to tear down the barriers between Earth and other dimensions when used in the proper ritual.
 * Opening the Seal of Danzalthar.
 * The blood of the Slayer was the only known cure for the Killer of the Dead, a poison specifically designed to kill vampires.
 * Mohra demon blood possessed potent healing properties.
 * The Sisterhood of Jaro Hull drank Connor's blood as part of a ritual to enhance their strength.
 * Flesh Magic

Color
While the majority of beings had red blood, blood could come in various colors depending on species.

Black : Turok Han Vampire, Bezoar

Green : Mohra Demon, Durslar Beast

Yellow : Skilosh Demon, Kungai Demon, Wig Lady, Suvolte Demon, Spike's crew

Purple : Bug Demon

White : Telepathic Demons