“Supply and demand,” I said. “There are limits to what outside forces can deliver to the mortal world. Think of the incoming power as water flowing through a pipeline. If a couple of people are using a rite once every couple of weeks, or every few years, there’s no problem pumping in enough magic to make it work. But if fifty thousand people are trying to use the rite all at once, there isn’t enough power in any one place to make it happen. It just comes out as a little dribble that tastes bad and smells funny.”
