Comments, feedback, and suggestions welcome.
Tier 1: Iron Skin (ST, Unit Enchantment, increases AC), Wall of Stone (S, City Enchantment, adds city walls or improves existing)
Tier 2: Stone Form (S, Unit Enchantment, target becomes construct-type*), Lodestone (S, Tile Enchantment, mineral as nightshade)
Tier 3: Earth's Embrace (T, Unit Enchantment, reduces movement to 0 but adds high damage resistance)
Tier 4: Elemental Armor (ST, Unit Enchantment, adds Elemental resistance)
Tier 5: Silent Sentinels (S, City Enchantment, adds guardians and -unrest in a city)
Tier 6: Steel Skin (ST, Unit Enchantment, increases AC, adds Mundane Resistance)
Tier 7: Iron Legion (S, Global Enchantment, all your units have Stone Skin)
Tier 8: Nature's Wrath (S, Global Enchantment, damages a SL's cities when he casts a curse/damage spell at you)
* no effects from negative/positive energy, immune to sneak attacks, bleeding, critical hits, mind-affecting spells