You do know there's a pattern to the die, right? Just watch the top number, the side of the die facing up. The numbers there go in a patten. Once you get that, with a little bit of practice, you'll get the timing, and soon you'll be rolling the number you want (or need) every time. Oh, and don't hit it with the Red Queen, use the Devil Bringer's buster attack. That sends it straight up and guarantees the right number. No other way seems to work.
Oh, and to stay on topic, I beat Berial with Nero finally. (And then died on the next level). Not sure why, but I play so much better with Dante. You think the lack of the devil bringer would be a disadvantage, but he definitely makes up for it with styles and how much faster he is.