Heroes season one, but beyond that, there's still a convention (and a time stream) that needs your help!
City of Heroes has put up their Hero-Con mission arc, "How To Save A Convention," and they need well armed heroes to go and put a stop to a villain that threatens time itself! While this mission line will probably be a lot of fun for all City of Heroes players, it will have a particularly strong meaning for anyone attending Hero-Con this year. The mission line supposedly ties into the live mission that will be going on at the convention (and it also hints at a big announcement being made at Hero-Con this year), so pay close attention to all of the details presented!
If you're looking for the mission, you can find it stored with the many other missions at Architect Entertainment.