In the Rampart, to upgrade a level 7 building, you need: 5*3 - for a level 3 Mage Guild, 5 - for a Unicorn Glade, 2*30 for an upgraded level 7 building. In total, 80 ore.
In the Stronghold, to upgrade a level 7 building, you need: 5 for Goblin Barracks, 5 for a Wolf Den, 10 for a Roc Nest, 2*10 for an upgraded level 7 building. In total, 40 ore, and if you consider that the first two buildings are often already built, then it's only 30 ore.
Speed and relentless attack - that's my tactic!!!!!!!!!!!!!
