Update:
According to TheWrap.com, Deathstroke will actually be the lead villain in Ben Affleck’s upcoming solo Batman film.
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HOLY AWESOMENESS, BATMAN!!!!!
Only moments ago, Ben Affleck released the following video (less than 30 seconds) on his official Twitter account. As far as we know, production has not yet started on Affleck’s Batman solo film, and so the theory is that this video is actually from the set of Justice League. Dark Knight News normally doesn’t post videos or pictures from films sets, as they are mostly taken by paparazzi. This video, however, seems to be coming directly from Ben Affleck himself.
— Ben Affleck (@BenAffleck) August 29, 2016
Could Deathstroke really be featured in the upcoming Justice League film? Time will tell!