Talus'ar, the Scroll of Fate is a magical scroll possessed by the archangel Itherael. It is an object that he consults in times of great need. Although Talus'ar is but a single scroll, accounts suggest that the information scrawled on the enchanted parchment changes based on the answers Itherael seeks. Allegedly, this is made possible by the vast number of crystals that Itherael possesses in the Library of Fate. Not all things are recorded in the scroll however.
In the minds of angels, all things that can be known are 'written', and it is through the scroll that these things can be known (as opposed to humanity, which is inquisitive by nature). However, Itherael never revealed his views on the ultimate fate of the Eternal Conflict, despite it being written within the scroll. He did not reveal that it was foretold that Heaven would lose when Diablo himself walked through the angels' realm. However, the fate of the nephalem was not recorded in the scroll, as they were not part of the natural order of Creation. And as such, the fate the scroll recorded was defied, and Diablo defeated.