The Crom Faeyr Scroll is dropped by Thaxll'ssillyia in the ruined temple of Amaunator. It is one of the components used in the making of Crom Faeyr, which is possibly the most powerful war hammer in the game. The other pieces are a Girdle of Frost Giant Strength, the Hands of Takkok, and the Hammer of Thunderbolts.
"This yellowed sheet of parchment describes the process used by the ancient dwarven smith Silverblade to forge the original Hammer of Thunderbolts, as well as the means by which he intended to continue to shape the weapon into its ultimate form. By the combining of the Hammer of Thunderbolts, gauntlets of ogre power, and a girdle of frost giant strength... and using the power of the hammer's true name "Crom Faeyr"... an ultimate weapon of destruction could still be completed using this scroll."