Subscriber content previewPhoto by Richard Shotwell/Invision/AP [enlarge] The four-day expo began in 1970 with a gathering of several hundred sci-fi and comics fans, but has grown to include cosplay contests, autograph booths, obstacle courses, concerts and panels covering everything from video games to fencing. SAN DIEGO (AP) — The Avengers appear set to return to Hall H as Marvel Studios uses Comic-Con International to build hype for the December release of “Avengers: Doomsday” — and chart a path forward as audience interest in superhero films has waned.