I think any spellwork that uses blood as an ingredient would classify as blood magic. I know many many spells that incorporate blood from many different traditions. It's especially prevalent in folk magic.
I think that's one of several methods, Gadamlu, if I were to use rune magick I would probably prefer to use chi instead of blood. Just feed the runes directly. However, I'm happy with the other arts I already use.
As Gadamlu said, LdyGry got it right. Just about any magick that calls for the use of your blood or the blood of a companion is blood magick.
sanguimancy is real and is very powerful. but also very taxing on the human body as some of it's more complex rituals involve draining yourself to the point of being near death. even then some of the extreme rituals actually involve things like murder and getting a large group of people to commit a very messy suicide.sure the effects are jaw dropping as to how real the results but the risk for most of them is to great. unless of course you work with a group that is willing to draw enough blood among them to meet the requirements and still stay alive.
and before anyone can ask it animals work, blood bags not so much,and no i wont explain the rituals due to not having my teachers consent.
"Now, the ideal behind Sanguine Magicks is that the essence that is detailed to be the life of all living entities harbors an amount of spiritual, (depending on interpretations: 'divine'), energies. In future posts and subjects I will provide more information on the subject of Sanguine Magick and practices involving sanguine essence."