What about a war-only spell available to mystics to boost WPA production? Something on the order of 25% or 50% increased wizard production with a short duration and high rune cost.

During war this would have minimal effect on AW, meaning AW is still an effective way to neutralize mystics. To use it during active war means wasting a lot of resources to keep it up, plus a raze or two on a mystic would drop the %guilds and base wizard production. Where I think this would be particularly useful is in the post-war CF period, where mystics could keep the spell up nearly 24-hrs allowing them to exit the CF with recovered WPA and more war-ready. Even at 40-50% guilds, it's difficult for a mystic to recover from deep AW runs within the 96 hour period.