A wizard's level limits the number of spells the wizards can prepare and cast. A wizard's high Intelligence score might allow the wizard to prepare a few extra spells. The wizard can prepare the same spell more than once, but each preparation counts as one spell toward the wizard's daily limit. To do so, the wizard must have an Intelligence score of at least 10 plus the spell's level.
Rest: To prepare daily spells a wizard must first sleep for 8 hours. The wizard does not have to slumber for every minute of the time, but must refrain from movement, combat, spellcasting, skill use, conversation, or any other fairly demanding physical or mental task during the rest period. If the wizard's rest is interrupted, each interruption adds 1 hour to the total amount of time the wizard has to rest in order to clear his or her mind, and the wizard must have at least 1 hour of rest immediately prior to preparing spells. If the wizard does not need to sleep for some reason, the character still must have 8 hours of restful calm before preparing any spells.
Recent Casting Limit/Rest Interruptions: When the wizard prepares spells for the coming day, all spells the wizard has cast within the last 8 hours count against the wizard's daily limit.
Preparation Environment: To prepare any spell, the wizard must have enough peace, quiet, and comfort to allow for proper concentration. The wizard's surroundings must be free from overt distractions, such as combat nearby or other loud noises. Exposure to inclement weather prevents the necessary concentration, as does any injury or failed saving throw the character might suffer while studying. Wizards also must have access to their spellbooks to study from and sufficient light to read them by.
Exception: A wizard can prepare a read magic spell even without a spellbook.
Spell Preparation Time: After resting, a wizard must study his or her spellbook to prepare any spells that day. If the wizard wants to prepare all the wizard's spells, the process takes 1 hour. Preparing some smaller portion of the wizard's daily capacity takes a proportionally smaller amount of time, but always at least 15 minutes.
Spell Selection and Preparation: Until the character prepares spells from the character's spellbook, the only spells a wizard has available to cast are the ones that the character already had prepared from the previous day and has not yet used. During the study period, a wizard chooses which spells to prepare. If a wizard already has spells prepared (from the previous day) that have not been cast, the character can abandon some or all of them to make room for new spells.
When preparing spells for the day, the wizard can leave some spell slots open. Later during that day, the wizard can repeat the preparation process as often as the character likes, time and circumstances permitting. During these extra sessions of preparation, a wizard can fill these unused spell slots. The character cannot, however, abandon a previously prepared spell to replace it with another one or fill a slot that is empty because the wizard has cast a spell in the meantime. That sort of preparation can only be done during the first study period after resting. Like the first session of the day, this preparation takes at least 15 minutes, and it takes longer if the wizard prepares more than one-quarter of the wizard's spells.
Prepared Spell Retention: Once a wizard prepares a spell, it remains in the character's mind until the character triggers it (or until the character abandons it). Upon casting, the spell is purged from the character's mind. Certain other events, such as the effects of magic items or special attacks from monsters, can wipe a prepared spell from a character's mind.
Death and Prepared Spell Retention: If the character dies, all spells stored in the character's mind are wiped away.
To decipher an arcane magical writing (such as a single spell in written form in another's spellbook or on a scroll), a character must make a successful Spellcraft check (DC 20 + the spell's level). If the skill check fails, the character cannot attempt to read that particular spell until the next day. A read magic spell automatically deciphers a magical writing without a skill check. If the person who created the magical writing is on hand to help the reader, success is also automatic.
Once a character deciphers a particular magical writing, the character does not need to decipher it again. Deciphering a magical writing allows the reader to identify the spell and gives some idea of its effects (as explained in the spell description). If the magical writing was a scroll and the reader can cast arcane spells, the character can attempt to use the scroll.
A wizard can use a borrowed spellbook to prepare a spell the character already knows and has recorded in the character's own spellbook, but preparation success is not assured. First, the wizard must decipher the writing in the book (see Arcane Magical Writings, above). Once a spell from another spellcaster's book is deciphered, the reader must make a successful Spellcraft check (DC 15 + spell's level) to prepare the spell. If the check succeeds, the wizard can prepare the spell. The wizard must repeat the check to prepare the spell again, no matter how many times the character has prepared the spell before. If the check fails, the character cannot try to prepare the spell from the same source again until the next day. (However, as explained above, the character does not need to repeat a check to decipher the writing.)
Wizards can add new spells to their spellbooks through several methods. If a wizard has chosen to specialize in a school of magic, the wizard can learn spells only from schools the character can cast.
Spells Copied from Another's Spellbook or a Scroll: A wizard can also add spells to the wizard's spellbook whenever the wizard encounters a new spell on a magic scroll or in another wizard's spellbook. No matter what the spell's source, the character must first decipher the magical writing (see Arcane Magical Writings, above). Next, the wizard must spend a day studying the spell. At the end of the day, the character must make a Spellcraft check (DC 15 + spell's level). A wizard who has specialized in a school of spells gains a +2 bonus to the check if the new spell is from the character's specialty school. The character cannot, however, learn any spells from the character's prohibited schools.
If the check succeeds, the wizard understands the spell and can copy it into the character's spellbook (see Writing a New Spell into a Spellbook, below). The process leaves a spellbook that was copied from unharmed, but a spell successfully copied from a magic scroll disappears from the scroll.
If the check fails, the wizard cannot understand the spell and cannot attempt to learn it again, even if the character studies it from another source, until the character gains another rank in Spellcraft. If the check fails, the character cannot copy the spell from another's spellbook, and the spell does not vanish from the scroll.
Independent Research: A wizard also can research a spell independently, duplicating an existing spell or creating an entirely new one.
Once a wizard understands a new spell, the wizard can record it into his or her spellbook.
Time: The process requires 1 day plus 1 additional day per spell level. Zero-level spells require 1 day.
Space in the Spellbook: A spell takes up 2 pages of the spellbook per spell level. A 0-level spell takes a single page. A spellbook has 100 pages.
Materials and Costs: Materials for writing the spell cost 100 gp per page.
Note that a wizard does not have to pay these costs in time or gold for the spells gained for free at each new level. The wizard adds these to the wizard's spellbook as part of the wizard's ongoing research.
A wizard can use the procedure for learning a spell to reconstruct a lost spellbook. If the character already has a particular spell prepared, the character can write it directly into a new book at a cost of 100 gp per page (as noted in Writing a New Spell into a Spellbook). The process wipes the prepared spell from the character's mind, just as casting it would. If the character does not have the spell prepared, the character can prepare it from a borrowed spellbook and then write it into a new book.
Duplicating an existing spellbook uses the same procedure as replacing it, except that the time requirement and cost per page are halved.
Some arcane spellcasters do not have spellbooks and do not prepare spells. Such a character's level limits the number of spells the character can cast.
Daily Readying of Spells: Each day these characters need 8 hours of rest (just like a wizard), after which they spend 15 minutes concentrating. A bard must sing or play an instrument of some kind while concentrating. Without such a period of rest the character does not regain the spell slots used up the day before.
Recent Casting Limit: As with wizards, any spells cast within
the last 8 hours count against the character's daily limit.
Adding Spells to a Sorcerer's or Bard's Repertoire: Most spellcasters that do not prepare spells like wizards gain new spells each time they attain new experience levels and never gain spells any other way.