Demigod Magic Resistance

	Pollux crouched next to a sleeping policeman. "I don't get it. Why didn't we fall asleep too? Why just the mortals?"
	"This is a huge spell," Silena Beauregard said. "The bigger the spell, the easier it is to resist. If you want to sleep millions of mortals, you've got to cast a very thin layer of magic. Sleeping demigods is much harder."
...
	"How'd you get through the magic defenses around the city?" Annabeth asked.
	"They slowed us down a bit," Chiron admitted, "but I think they're intended mostly to keep mortals out. Kronos doesn't want puny humans getting in the way of his great victory."