Complex sentence: At Disney's 2013 D23 event it was announced that James Cameron's Avatar would be transformed into Avatar Land, a themed area at Disney's Animal Kingdom in Lake Buena Vista, Florida.
Split into simpler sentences: At Disney's 2013 D23 event, it was announced that a theme park will be based on "Avatar," which will be called "Avatar Land". It will be a themed area at Disney's Animal Kingdom in Lake Buena Vista, Florida.