Sweden's Level 3 "Fine Steel for Tools and Guns" ability causes Towns to deal 3 Damage instead of 2 and Cities to deal 5 Damage instead of 3. The usual amount of Defend is not enough! Also, their Level 1 "Heavy Mining" effect adds extra Blight if they deal at least 6 Damage to the land during Ravage. Blight added this way does not cause cascades, though.

Russia Level 1 causes Explorers to deal 2 Damage instead of 1.

Furthermore, there are several Event cards that can increase the damage Invaders do during Ravage.