Pathos Verdes III had two sons, whom he buried in two separate locations in Pandora's Temple. In order to traverse the temple, one would need to find their corpses, and take their skulls. Their skulls then function as keys. Kratos finds the bodies of both sons, and takes both their skulls. The first skull is used to unlock a doorway into the second Ring of Pandora, and the second skull is used to drain out the water in the third ring. Verdes III was ingenious in his idea to implement skulls as keys, but he most likely did this because of his growing insanity.