I'm counting on blood thorn + astral weapon for Tuna's SC roundup
If a unit has high enough strength, and you throw in armor piercing or negating magic, the bloodthorn can be super effective. It's also great against billions of lightly armored (living) enemies.
It can be hard to kill life-drain-capable SCs without ready access to nonliving troops. And weapons aren't the only things that drain life...
As for 30 vans killing an SC, I should hope so. That costs 2100 gold, 480 resources, and 30 holy (plus unquantifiable cost of pretender blessing paths), compared to an SC that might cost 10 gems + 30 gems for equipment. 30 centaurs are more reasonable but have a much lower chance of success. Mictlan, Tien Chi, Ermor, Ulm, Machaka, Man, and other countries without strong elites or only highly resource-intensive elites can't fight mid-level SCs effectively with national troops. Some people say "That's good, that's the way it should be." But I don't like the game to degenerate to an SC race.