There are all kinds of vocabulary builders, and I think you invented a new one in your dream.

I tried to take some guesses, got stuck, and consulted wordweaverlynn, who happened to be handy. She pointed out the Flesch Reading Ease scale (easily findable on the Web and available with the Microsoft Word grammar checker). She and I guess that an average novel has at least 5,000 different words, and that a writer who had that as a goal could make it 15,000 without much trouble.

Now I want to run The Shadow of the Torturer through a Flesch calculator.