The Spirit of the Great Fever is a vaccine, and it’s not something you drink like a potion, because that way it wouldn’t work. It needs to go directly into the body to prepare the defenders who will fight off the Invisible Warriors, to stop them from making us sick. To get the Spirit of the Great Fever working hard inside us, what’s needed is a tiny prick in the arm with a very sharp needle. Ubloa was a bit frightened before the Wizard pricked her arm, so she squeezed her eyes shut. But she only felt a tiny little pinprick – the needle didn’t hurt at all!