While you have your Spellbook, you can spend 10 minutes studying
Spells that you have written in it. You can replace ANY prepared
Spell with another. Known
Spells (from a subclass) cannot be replaced.
You trace intricate runes on the worn pages of your spellbook, each symbol glowing faintly as you study. The arcane symbols shift and twist, ready to reveal new secrets and hidden powers.