Via Comic-con freebie postersComic-Con kicked off last night with the usual Wednesday preview of the exhibition hall. Among the freebies made available to attendees were some nifty new concept art posters from Avengers: Age Of Ultron, featuring Scarlet Witch in action and Iron Man battling the titular menace. {Avengers : Age Of Ultron Concept Art Posters}With Marvel expected to put on its usual big show this coming Saturday (with additional panels for the company’s ever-expanding universe of TV shows and more), it is naturally trying to keep Joss Whedon’s superhero sequel front and centre in fans’ imaginations – not that it really needs much help.The film finds Iron Man, Thor, Cap and the rest a little weary of constantly having to save the day, so Tony Stark (Robert Downey Jr.) hits upon the idea of a robotic police force led by super-smart artificial intelligence Ultron (voiced and performed in the film by James Spader).