Whelp, time for everyone to start living in space stations! Seriously, a weapon that can hit and crack multiple planets from outside the star system? There's little to no planetary defense against that! There's hardly even any warning that it's headed for you! The best defense I can think of (besides staying hidden) is gravitational deflection of some kind to unpredictably bend the beam before it gets close. No one has yet shown the ability to move black holes around at will though, so the best that could happen there is a warning shot or few while the Peace Moon walks its shots around the local star or black hole.

I do have to wonder how the heck the Cataclysm Beam manages to stay together enough to do this kind of damage. Especially since it's designed to split up once the beam gets to the target system. Maybe this isn't just a giant plasma blast? I know I know, it's just a movie/comic and it's Star Wars at that. But with the interstellar distances that require hyperdrives for people to cross those distances, this should either not be that dangerous to those planets or it should have done a ton of damage to the Peace Moon surface with all the people watching it from there. Not to mention the fact that we can actually see the beam traveling from the surface of another planet while it's day and through a blue sky atmosphere.

I think this is another one of those instances where if I'd actually watched the movie first, I would have completely ignored or forgiven the issues I've come up with here. Get some appropriately dramatic music playing (and not have a Ben-quality-level speech from General Hux), and I could see myself focusing entirely on the What is going on rather than the How is it going on. Like the original Death Star use; it's only like 20 seconds long too! There's the wind-up with all the button pushing, then the giant green laser beam in the tube, followed by the emitter dish "growing a cone" of green lasers, and finishing with the whole beam firing out and destroying Alderaan. A text description feels so limited in comparison, and that doesn't even count the whole interrogation just before! Even if I much prefer the plot of Darths & Droids (huge improvement to everything, Episode I especially), I do think a static medium, like a comic, will necessarily lack the some of the metaphorical punch in scenes like this.