Thank you for the answer 
, and thank you Prince, sorry I couldn't get back to you.
In my epilogue, I wanted the reader to know that the city they are in, is now a city o heroes.
Word of caution. The phrase "City of Heroes" is trademark protected but not copyright protected, as VV indicated, which allows you to use the phrase generically (which is why she said don't capitalize or use as a title, which would turn it into a proper noun, which would be more shaky). But the City of Heroes game content and the constellation of books and comics are copyright protected, and copyright protection is a bit tricky. Trademark protection is pretty straight forward: don't use the mark to identify your own products, brand, or company, or attempt to confuse your use with the protected use. That's why I can use the phrase "City of Heroes" here: I'm referencing the real product, but I'm not using the phrase to identify one of my products or my company itself. I'm not using the mark to conduct business, I'm just using the phrase to discuss the subject.
Copyright protection has more judgment calls, to put it one way. Using the phrase "city of heroes" is not going to cause problems unto itself, but you need to be careful you don't reference too many other City of Heroes content obliquely. If there is too much similarity between elements of your story and City of Heroes game or other content, a nod/wink use of the phrase could become the straw that breaks the camel's back.
As long as the rest of the story is an original work with no connection to City of Heroes except for obvious generic story elements, the phrase itself shouldn't be a problem. Disclaimer: I am not a copyright attorney.
