You made a good name for yourself in part because you knew how to prepare for the challenges before you, even if your natural magical abilities lend themselves less to preparation and more to spontaneity.
Benefit: When you regain spell slots at the start of the day, you may opt to prepare one spell you don’t know in place of a daily spell slot 1 level higher than the prepared spell’s level. To do so, you must have access to the selected spell on a scroll or in a spellbook, and the spell must be on your spell list (even if it is not one of your spells known). This process takes 10 minutes per spell level of the selected spell.
You can cast the selected spell a single time, expending the spell slot as though it were a known spell being cast by you. Preparing a spell in this manner expends a scroll but not a spellbook. A spell prepared in this way is considered its actual level rather than the level of the spell slot expended. You can apply metamagic feats to the spell as normal, as long as the spell’s actual level plus the increases from metamagic feats is 1 level lower than the highest-level spell you can cast. For example, a 12th-level sorcerer with this feat, a scroll of fireball, and the Empower Spell metamagic feat could prepare an empowered fireball spell in her 6th-level spell slot.
Special: If you spontaneously cast arcane spells, you must have an Intelligence score of at least 13 to take this feat.
If you spontaneously cast divine spells, you must have a Wisdom score of at least 13 to take this feat.
If you have both arcane and divine spellcasting classes, you can use this feat to prepare a spell using a given class’s spell slot as long as you meet the associated ability score prerequisite.
Pathfinder Player Companion: Pathfinder Society Primer © 2013, Paizo Publishing, LLC; Authors: John Compton and Mark Moreland.