Tales of the Bloodstone Lands
Mastering a Foreign Spellbook
Variant: Mastering Another Wizard’s Spellbook
You cannot prepare spells from another wizard’s spellbook, but a wizard who captures an enemy’s spellbook may choose to take the time and energy necessary to master that spellbook and call it his own.
For each spell in the enemy spellbook, the process of mastering the spell takes 2 hours and costs 10 gp per level of the spell. This must be done for each spell in the foreign spellbook. Once you have mastered that spell, you may prepare it from the foreign spellbook as normal.