Still working on it. I've gotten up to Ballos before, but usually I die on his first form. I got up to his final form once, but I was rather low on health, so I just ended up dying to the rotating things.
Interestingly enough, I had a save where I didn't get the missile launcher at all. When I got to Hell, that missile launcher container contained the normal launcher and 100 missiles. I accidentally deleted the save though.