I am guessing that the beam and destruction can be attributes to the large object on the right of the new poster they just released. Some rumors (take them for what you will) say it will be named the Starkiller, finally using that name in a canon source.

1. Kylo is wearing a mask/helmet in all of the trailers/pictures. Although this could be explained as a "respirator" or something, from a director's standpoint it would most likely be because we'd recognize the actor/face (and Mark Hamill is definitely a recognizable person). Of course, masks do look badass, so it could just be character design.

2. We have seen very few shots or pictures of Luke himself, who should obviously be a major character. Now I'm wondering if the reason we have so few shots of "Luke" could be because he turns to the dark side or gets killed off early on, but it seems to me like Luke would be too strong to just die.

3. Kylo Ren has a weird obsession with continuing "your legacy" (presumably the legacy of Darth Vader), but also owns Vader's disfigured mask. Although this could be explained as extreme fanboyism, and retrieving the mask, it seems more likely to me for Luke to keep it to remember his father. Also, maybe Ren doesn't mean the legacy of Darth Vader, but of Anakin Skywalker.

4. Luke would definitely have the technical know-how to build a unique lightsaber and use it effectively, which would probably be very rare in an era where there are so few jedi.

5. In ROTJ, Luke was dangerously close to joining the dark side, but Emperor Palpatine forsaw his change. Now, to me, the emperor seemed like a very strong force-wielder (hiding the sith presence and his identity from the ENTIRE jedi order for so long) who wouldn't see a false or possible future and mistake it as fact. What if he was simply looking too far into the future when he got this premonition.

Luke voluntarily switches to the Dark Side in order to better understand it and to try and destroy it after.