Filmmaker Karan Johar has already announced that he is collaborating with the megastar Amitabh Bachchan and actors Ranbir Kapoor and Alia Bhatt for a fantasy adventure trilogy called "Brahmastra". Karan Johar also said that he will announce a new film with actress Sonakshi Sinha within the next two weeks. Their last collaboration was "Ittefaq".
