What happens if I play Urborg, Kormus Bell, and Humility? Or maybe Nature's Revolt and Humility? Anyway, do the lands lose their ability to tap for mana? I don't really understand how lands get this ability. Is it an ability on the card, so Humility takes it away, or is it granted by the -Swamp or -Mountain subtype, and in that case, does Humility take away that subtype?