The thing is with trolls, having tried to have a different perspective on them;
Here is a person. Obviously troubled in some way, wants to shock people, because they feel numb.
Now you can condemn that person. You can push them away. And they will go try to harm someone else.
But you also have the power, as a child of God, to change a persons heart, to try and understand them, to make them see themselves.
I only say this because I tried this different perspective. And in empathy, it was sad to see just how troubled, and how much abuse and terror, this person had been through. And in not being able to deal with it, they became a little terror themselves, because they wanted to be judged. So the seeking out and by appearance, destructive nature, was more engaging with trying to be judged as brutally as possible, and feeling nothing from it, feeling powerful, yet deeply inside, powerless.
So yes, you can protect yourself, or a site, or a place from them - but at the same time, maybe you can help someone be a better person too, who is greatly in need of love rather than the appearance of judgement or hate. And out of that, maybe someone else won't become a victim of them.