The Eleven Pieces of the Gate of Bones.
The entrance to the spirit world was once an unregulated, writhing mass of spirits pouring into the world. The people were helpless before the onslaught of daemons and unclean spirits that came through the rift, called the Mouth of Geddith, named so after a fearsome and terrible devil. In 1005, the Ardent Temple finally came up with a plan to stem the tide, bringing the flow of daemons to a halt, called the Gate of Bones. Taking the bodies of over a hundred saints, they rotted them down to only bones and constructed from them a gate before the rift, the holy sanctity of the saints interred within keeping the daemons at bay through concession with the spirits.
But, though the daemons were convinced by the words of the saints within, a single devil could not be swayed to leave the world of Man alone, and he sent forth agents of his own to break the gate. However, they could only manage to steal away eleven pieces, all of them from saints who turned from the Temple and held hate in their hearts for the sacrifice they had been forced into. As much as they wished, the spirits of this devil - said to be Geddith himself - could not break the bones of the saints, and so instead, they hid them.
The gap was enough to allow the daemons to once again traffic into the world of Man, to cause mischief, death, or both. The Eleven Pieces of the Saint's Gate remain somewhere in the world, and it will take a convincing individual to persuade them to come back to do their duty - or a powerful one to force them to.