All you do to win a debate with Trump is remind him of his past, and the things he said...
“I’ve known Jeff for 15 years. Terrific guy,’’ Trump told New York magazine in a 2002 profile of Epstein written three years before Epstein began to be investigated. “He’s a lot of fun to be with. It is even said that he likes beautiful women as much as I do, and many of them are on the younger side. No doubt about it — Jeffrey enjoys his social life.”
Just mention Jeffrey Epstein’s name in the debate tonight, and watch as Trump goes white as a ghost!
Given that most people don't know who Jeffrey Epstein is, Trump will probably survive.
My first reaction was that what candidates can do in a debate is different from what anonymous internet posters can get away with, but on reflection a candidate probably could bring up something like this if his campaign has done the groundwork and prepared at least some of the media for the reference.
Throw something like that into the debate without preparing part of the audience and it will go over like a lead balloon.