Don't take me for a fool; I know the roarmulus twins have to be hit wit missiles before they can take damage. The bug is after they are hit with rockets and lie down on the playing feild. I saw my brother, IGN sirkibbles, playing the bosses becuase he was complaining about their sheild. I walked up and saw that even though it was knocked out, it took no damage and made that "plink" noise when you hit an invincible or sheilded target. So I watched and noticed sirkibbles first hits would deal damage, but the latter ones wouldn't. I soon figured out that his freind kept hitting it with a charged torkia-line weapon, and that after being stunned it couldnt take damage. I told him to tell his freind to stop using charges, and everything went to normal. So I think it's safe to say stunning one of the twins while they are prone renders them invincible. At least in this case.