'The use of blood in magical practice is as ancient as sorcery itself.

Practitioners have long used their own blood to empower wards or bindings,

And the ritual sacrifice of animals as offerings to empower rituals and prayers has existed since time immemorial.

But there is a line beyond which decent folk must not cross,

And the sacrifice of other sentient folk has always been considered among the greatest evils one can commit.'

- Magister Brennan, Fundamentals of Sorcery