what is a good topic sentence for foreshadowing for the lord of the flies?

Hey, you have your question under the wrong category. In any case, there are different ways to start this off. In an essay, you should always move from the general to the specific. So, your topic sentence should follow a general introductory line about foreshadowing. Consider something like this,

Foreshadowing is a literary tool that William Golding uses extensively in his novel Lord of the Flies. (You should underline the title of the book)

Then go on to the specific points that you want to cover.