Given to the Archmage Luthien Fallensbane II for defeating the fallen
god turned demi-lich Mykryl. It knows all the spells known to Mystra
and new spell will appear within its pages in 1d4 days of Mystra's
knowledge of the spell.

Grants a +5 Spellcraft Check while held
Grants a +10 Knowledge (Arcane) while held

In addition to those abilities the following spells may be cast once
per day as a 20th level Wizard

Greater Teleport
Planeshift
Gate
Protection from Spells

Only a chosen of Mystra may benefit from any of the books abilities.
To anyone else it is just a tome full of blank pages. Any non Chosen
of Mystra can see illegabil words and must make a will save (DC 40)
or go insane as the spell.