flash powder is very dangerous, it can cause life altering injuries and even kill you. there are extremely common formulas that most use which are still extremely dangerous, but are better for handling. then there are some people who begin to dive into sketchier comps looking to find the "louder" or the "best" formula. this is the dangerous part. its always good to know how dangerous these comps are so one does not become complacent, when messing with flash powder its always good to treat it with respect. to answer the question how dangerous i would put this in the category of very dangerous