[Epaminondas]

I agree that the Staff of Corrosion is a nasty item on a cheap commander. Further, it also appears that a commander equipped such a way likely has more utility (in terms of damage potential and survivability) than most low level mages in the early game. Nonetheless, I am not sure if they do "survive most arrow storms." In fact, their relative vulnerability is why I've stopped equipping them with two-handed staffs or bows and have opted for a shield and one-handed wands instead (like the Scepter of Authority or the Wand of Wild Fire or something like that). You get slightly less damage but far better survivability with a shield. Of course, all this seems to me early game talk; once you get decent self-protection buff spells and nasty AoE-type of spells on your mages, the latter ought to outdamage and even outlast a conventional commander.