Golden Kingdom's ancient-Egypt desert map runs entirely on Curse Resistance. Digging Strongholds and monsters each have a required resistance value, and falling short doesn't just slow you down - your damage drops by up to 99.9% no matter how high your Power number is. This is the one system you cannot skip or delay.
Curse Resistance comes from the Curse Research Lab, powered by Holy Water from Blessing Fountains, which in turn run on Mithril (mostly earned from zombie first-kills, once per level). Upgrade all four Blessing Fountains evenly before pushing any single one further - it's the cheaper overall path.
A useful trick for lower-spending members: in a rally, the LEADER's Curse Resistance applies to the whole group, not each individual's own. Many alliances designate one strong "Resistance Leader" who rushes the Curse Research Lab and leads every Digging Stronghold rally, so everyone benefits even before their own resistance catches up.