Counter-speech
Replying in public so that onlookers see a claim answered, rather than to persuade the person who made it — a narrower and rarer case than most advice about replying implies.
A decision tree for choosing which response strategy matches your situation.
This question comes first because getting it wrong costs the most. If someone is threatening you, turning up, or seems to know where you are, none of the rest of this applies.
Several accounts arriving together is not the case the advice was built for. Neither, it is worth saying, is one person who will not stop: a single fixated individual is the harder case, not the reassuring one.
If the point is to perform something for onlookers, your silence does not end the performance.
A factual claim in front of people who will remember it is different from an insult.
The amplification argument is much stronger for accounts with reach than for someone with two hundred followers.
This is a legitimate input, not a weakness. Consider your emotional toll, time, and other effects of engaging.
Each strategy works in specific situations and fails in others. Find the one that matches yours.
Replying in public so that onlookers see a claim answered, rather than to persuade the person who made it — a narrower and rarer case than most advice about replying implies.
Writing down what happened, when it happened and who saw it — a practice borrowed from guidance about stalking and harassment, not tested for the ordinary tactics documented elsewhere on this site.
Declining to reply, so that provocation produces no reaction and no audience. The most repeated advice on the internet, and among the least examined.
Responding in a deliberately neutral, minimal and emotionally flat way, so that provoking you stops producing anything worth having.