OK, so what's so crazy about formation 3C 321, and what makes it deserving of the title "Death Star Galaxy"? Well, for starters, the supermassive black hole at the center of this galaxy is blasting apart a nearby orbiting galaxy. Here's an artist's conception, so you can see the sort of thing we're talking about:
Just so we're clear, here's a breakdown of the situation. There's a supermassive black hole at the center of a galaxy, but no ordinary supermassive black hole: this one is emitting a jet of incredibly intense EM radiation. How intense? Intense enough to move stars. While jet emissions from black holes and other stellar formations are not rare, what is rare is to see one firing point-blank into a nearby celestial formation. Like, these galaxies are only about as far from each other as we are from the center of the Milky Way.
Heroes in lab coats are still trying to figure out what exactly causes these kinds of jets - I suspect the right hand rule, but the Devil's in the details. One strong possibility, though, is that the very process of blasting apart the neighboring galaxy will cause it to be re-formed around the area where the jet peters out. That is, assuming that the galaxies don't collide first. Dammit, why can't I live for billions of years so I can watch this sort of scene play out?
Here's a really cool animation showing how this plays out and giving a sense of scale to the operation: it starts by the event horizon of the supermassive black hole, then zooms out until you can see the whole scene. Check it out!