So yesterday was my guild's second attempt on this boss, and we've encountered this: almost every time when it was about to use Defensive Systems, it would start dropping lightning pillars on top of people that were standing on the tank platform. And when I say 'about to', I mean before the knockback, before the channeling gauge would appear, sometimes even while the second Double Destruction was still in the middle of it's channeling (!!!). The first time we fought it, it did nothing of this sort. I've looked over some youtube videos, and found both cases of the supposed correct and incorrect pillar dropping. So I'm wondering, is it random, a bug, or is there a mechanic that makes it happen that we managed to avoid the first time we fought it?
Our fight: http://www.youtube.com/watch?v=jZyY5AJHYzM
More broken pillars: http://www.youtube.com/watch?v=S_v8A6RXuWI
Not broken pillars: http://www.youtube.com/watch?v=I6SA0JokugI http://www.youtube.com/watch?v=uLPRzt2jPGY