If you want to buy 'evil blood,' A24's creepy horror-movie website has you covered
"It's a website you can visit where [Bring Her Back character] Laura purchased this tape from. It's sort of like a dark-web-feeling marketplace where they sell all these fucked-up occult items."
How to Become an Evil Wizard in the Middle Ages: The Secrets of Picatrix - Medievalists.net
Picatrix offers a wide variety of magical spells and creations, including summoning spirits, building talismans, and concocting cures (or causes) for many ailments.