A colon is indeed expected to introduce a list but the text preceding it must constitute an independent clause making up a sentence that can stand alone.Use a colon after an independent clause that introduces and states the nature of the list that [ follows. The preceding sentence must include a phrase that serves as a generalizing term common to the list elements ]
To take revenge on the people in Florence who hurt him . He stuffed all his personal and political enemies in various choice corners of hell .
Hope it’s help !!!
Setting: Greg’s house (which is on Upper Surrey street)
Time: middle school