It's basically witchcraft 101. What you put out into the world is what you get back.
Listen, from both an ethical and practical standpoint stealing someone else's blood just isn't smart. I KNOW what magical properties my blood has and how to use it, so it just makes sense to use mine. Getting mystery blood from somewhere else opens you up to unforeseen variables, not to mention the act of taking someone else's blood opens you up to negative intent and will affect the ritual/magic.
no subject
Listen, from both an ethical and practical standpoint stealing someone else's blood just isn't smart. I KNOW what magical properties my blood has and how to use it, so it just makes sense to use mine. Getting mystery blood from somewhere else opens you up to unforeseen variables, not to mention the act of taking someone else's blood opens you up to negative intent and will affect the ritual/magic.