[MaxWilson]

I've never tried Rust Mist, but if you have the paths for it I expect it's just as good as Destruction, which is to say it's good if you don't care about friendly fire hits. Chaff + archers vs. expensive vans sounds like a situation where you don't care about friendly fire.

Edit: And don't forget that you have access to Strength of Giants and Weapons of Sharpness, too. WoS is good if you *are* worried about friendly fire (I hate it when I Destruction my own troops)--one cast should cover most of your army and a second one in the first round of battle will cover PD, too.

-Max