Would you be worried???

In order to defeat the strong, you have to be stronger, but not fight fire with fire. I wouldn't be worried, because sometimes doing the opposite of that caster like if they put a hex on you, then you cleanse yourself (or reflect the hex back), if they try to hurt you, then use a protection spell. Always counter every move with something else, like in a game of chess, every move counts and builds up to either success or failure.