Geoff "Jeff" Johns showed off the first six pages of Doomsday Clock at New York Comic Con. The big reveal on page six:
That's right, Rorschach is back! The crowd cheered at the reveal, which pleased Johns. As Johns revealed at the panel, the only book you need to read before Doomsday Clock is Watchmen.
You can read the full lettered NYCC Doomsday Clock ashcan here.