Brainflight

Brainflight was an alchemical substance that caused hallucinations, addiction, wildly erratic behaviour, and over time, a personality breakdown rendering the user chaotic evil. It may likely have had other effects as well. The substance was likely difficult to synthesize, requiring a combination of solid alchemical and herbal skills; hedge wizards who valued money more than other people's lives traded in it, as did some other lowlives. On the other hand, while it probably contained difficult to get ingredients, it might not have been that difficult to make afterwards. It sold for about 500 gold pieces.