[Gregstrom]

Thunder Strike is a good bet if you can mass enough casters. It has AoE fatigue as a secondary effect, which will help a little if you're doing Curse of Stones (although they tend to have high MR, so a lot of the fatiguing effects you can cast will be resisted.

Iron Warriors is not going to help too much, because the high Str on Ashdod giants will still punch through armour. False Fetters/Earth Meld may help a little, but Destruction would make a big difference if you can cast it a few times.