There should be fairies, with a vulnerability to iron and other materials that are processed into unnatural states. Things like swords, bullets, chemical weapons, motor vehiclesâŚ
Actually, thinking on it, if the fey had been all but driven to extinction by industrialisation, and then all these visitors show up, wreck up all the human industry, and then proceed to be highly weaponised entities that are essentially composed naturally(by their standards) and not using much in the way of technology, it would be a real opportunity to recover the world in the name of magic. They could even be master-minding the giant animals. Ehh, but are there any fairy-based cataclysms in popular culture? Hrmm, wasnât King Arthur supposed to return? Is anyone familiar with the specifics? Did Ragnarok have anything fun like that?