The troubles began when the Emperor fell ill. He called a great conclave of wizards to assist him in determining which of his many relatives should be his heir.
Hearing of the Emperor’s illness and the gathering of wizards, Shim Gorad, Dark Lord of the Southern Lands, struck at those gathered at the Conclave. One of his magic-resistant monstrosities attacked all present, and slew the Emperor and the majority of the wizards gathered there, in one blow depriving the Empire of Light of most of their most powerful wizards.
In the months that followed, many of the priests of the Church of the Light began to grow despondent and depressed, and before long a rash of suicides began to thin the numbers of the priests.
Beginning shortly after the suicides, extraplanar beings began to appear without apparent summoning being employed. They would annihilate a village, then disappear to their plane of origin.
Due to the suicides and the civic authorities’ inability to do more then try to hold the Empire together in the face of these attacks, the Church of the Light has put out word that it needs adventurers to gather several artifacts for some great working.