This is the oldest category, predating the internet by millennia. Here, you will find digitized grimiores (books of magic) that have been banned by religious authorities, detailed instructions for rituals involving blood or sacrifice, and modern interpretations of chaos magic. Entire wikis are dedicated to the "lesser key of Solomon," necromancy, and "reality shifting" techniques considered dangerous by practitioners of more traditional occultism.
Curiosity is not a crime, but intent and action are. Searching for or accessing a Secret Taboo Wiki can expose you to significant risk: secret taboo wiki
If your interest is anthropological rather than predatory, there are legal, ethical, and fascinating alternatives to the dark web's secret wikis: This is the oldest category, predating the internet