Yeah with the new magic system implemented in Wildmana it would make sense to make most of the AC effects go hand in hand with the system. Make it so that for every point above 0 it benefits dark magic(Via reduced costs/maintenance), for every point below, it benefits light magic. Obviously you'd have to make it so that The AC counter can go into the negatives. Make it so that the global enchantments can prevent hell terrain spread (with a higher cost if you're evil) and as the AC rises the cost of these enchantments will go up accordingly till you're overwhelmed. The way you can currently(Pre 9.0) just go out and sanctify terrain makes most of the AC system ignorable. The current system with no incentive to raise it makes it pointless game-play wise.