Answer not a fool according to his folly, lest thou also be like unto him.
Answer a fool according to his folly, lest he be wise in his own conceit.
Most of the time I don't engage trolls: I simply ignore them and move along. I've never been a fan of the exchanging of the throwing of drinks in another's face, let alone the back lot brawl, as exciting as they may seem to be to some at the time. Dry cleaning and medical bills are expensive, and life insurance might not pay out—as if that's of any real concern to those of us who like to survive. Responding in kind to online trolling is much the same in my opinion, and I have no desire to waste my time in this manner. — "Answer not a fool…"
However, if there are points being made in a conversation that are demonstrably incorrect or deceptive, I'll address those points directly, refusing to return in kind their harassment, particularly personal (ad hominem) and "you too" (tu quoque) arguments, focusing on the issues and not the person. In my experience, this is usually the best and fastest way to discourage most trolling, and of course, there's always the option to mute or block them and delete their comments if they persist. — "Answer a fool…"
Who'd have thought that a 3,400 year old pair of seemingly contradictory proverbs could provide so much wisdom in our post-modern world? 😉