A single Leman Russ Punisher could do it, though admittedly it isn't very likely. A squadron of Punishers certainly could, though, or a single mob of lootaz. But it's a very likely scenario that a vehicle with multiple void shields gets hit more times than it has shields. As I said, I don't have my books with me at the moment, but intuitively it doesn't seem right that if I have three void shields and get hit by five lascannons from a single unit, the very worst that can happen is that I lose all three shields.