Needs review
Source: Player's Handbook

Description: You are so intimately familiar with certain spells that you don't need a spellbook to prepare them anymore.

Prerequisites: Prepared Arcane Caster Level 1

Each time you take this feat, choose a number of spells equal to your Intelligence modifier that you already know. From that point on, you can prepare these spells without referring to a spellbook.

Normal

Without this feat, you must use a spellbook to prepare all your spells, except read magic.