This isn’t to throw shade on any spesific person that came up with this question. I have seen some people having this concern before and asking for help.
First thing first, it is possible that someone is really gonna do it and they are letting you know. In that case, I hope both of your offense and defense skills are sharp.
But most of the time, this is either a larp or overblown ego case, as I hope my examples will give a clue. Just my observations and experiences.
Okay , for example : I am darkness incarnate from upteenth dimension.
Ask yourself, why is Mr. Darkness Incarnate over here, so hellbent on proving you a point, instead of going ahaed and literally proving the point? Answer is they are either crazy, larping, or trolls. Surely such a being should see you like an ant, no? Then why isn’t he crushing you with his boot?
Their influence ends the moment you have a laugh at them, and ignore them. They probably have self confidence issues and have to boast themselves, in order to keep their tiny fragile ego stable; instead of putting in work and becoming better.
Very possible they were trolling around, as well.
Most of the time people do not tell you that they will do black magick on you, because having the upper hand is their weapon. Wild cats do not go roaring around forest when they are hunting. No need to make the prey alert.
A genuine dangerous case may be, is that, the attacker enjoys seeing you in a panicked state. If you are panicking, he already has the upper hand on you whether they have done anything to you or not anyways. Grow some balls. And be prepared for anything, anytime anyways. Protection is a must.
Learn banishing and protection rites, ally with powerful spirits if possible. I don’t see a point of telling you how to do those, as there is a million of posts about these subjects on the forum anyways.
Best of luck, no need to be scared.