Create expensive units, 500k each but 500k a/d and destructible at a very low rate. It will make the casualty decrease relevant, gold relevant, and strength variable without having to inflate stats to the point where two years of work is irrelevant after one event if you have enough money.
Also, make boosts exclusive to war. Don't ruin the most innovative thing you've done in the game by marginalizing their importance by lowering the guild rewards and raising the quest rewards.
Just some constructive criticism.