Making trailers is a fine art. They need to sell the film, introduce the characters, generate intrigue, and do all of this without giving away too many spoilers.
For all of the teething problems and growing pains the DC movie series has suffered, Justice League is a fine example of this art. The movie's trailers focus on the heroes, show snippets of action and establish the tone, but are relatively free of plot details.
It isn't often that DC gets one over on bitter rival Marvel on the big screen these days, but that's exactly what it's done here since the House of M's next film, Thor: Ragnarok, has been spoiled to death during its promotional campaign.
The entire plot of the thunder god's next adventure has been outed almost entirely by its trailers. All that's left to reveal is how it ends, but no doubt Avengers: Infinity War's debut trailer will offer a few clues about that when it finally arrives.
This is a problem that has dogged Marvel Cinematic Universe movies dating back to the original Iron Man. Their trailers are never anything short of epic, but they just can't hold their own water.