HBO and HBO Max preview trailer has been revealed, showing footage from Game Of Thrones spin-off House Of The Dragon.The show, which is yet to receive an official release date, features early in the trailer, with footage showing stars Matt Smith, Olivia Cooke and a huge dragon’s head.The 10-episode series is set 300 years before the timeline of Game Of Thrones and follows the House Targaryen up to a bloody civil war called the Dance of Dragons, which threatens to end the Targaryen reign.The