Worldkeepers

Worldkeepers are objects that, when used together, act as a key between the Book World and the Real World. Three were hidden in the Book World, and if they pass through the Door of Ways at exactly the same time, they will act as a locking mechanism, permanently sealing of the two worlds from each other.

Worldkeepers

 * The first worldkeeper was Gilbert's heart, and by possessing the heart one could travel back in time once and fix a mistake they made.

Appearances

 * House of Secrets 3: Clash of the Worlds