Editing Landsoftheblacksea:Main Page/house rules (section)

=== Magic Users (including Bards & Illusionists) ===
Mages within the Lands of the Black Sea are typically trained within a Magical School.  These schools are typically located either in large urban settings, or are secreted in inaccessible, difficult to find locales. Some magical schools specialize in certain Schools of Magic (see The Complete Wizard), giving them advantages within that sphere, but restricting them from using spells in the opposition sphere(s).  Illusionists in the Lands of the Black Sea are considered Mages that specialize to the Sphere of Illusion (e.g., no separate class).

Wizards, Bards, and other users of arcane magic still must abide by the core rules that dictate their ability to learn a given spell that is found, based on their intelligence score. An arcane spellcaster must spend some time every day studying from their spell book in order to be able to cast these spells. The amount of time needed for the spellcaster to do so is approximately one hour per day, regardless of the number of spells he has. A simple "I spend some time studying my spell book" announcement by your player is sufficient to consider it done. It can also be divided into many separate sessions of time during the day like in the morning, at lunch, before going to bed, etc. 

If 5 days in a row goes by without the player being able to study his spell book, there is a chance that some spells may be forgotten temporarily. This chance is based on the spellcaster's Intelligence score in the following manner: In this situation, when a spellcaster attempts to cast a spell, a cross-check against the Intelligence of the spellcaster with the "Chance to Learn Spell" column in the AD&D Player's Handbook is made. The percentage shown is deducted from 100%. The result is the percentage of chance that the spellcaster has forgotten the spell. Spells forgotten in this manner are subject to ruling by the DM – spells’ that are frequently or recently used are less likely to be forgotten than a spell the wizard has never actually cast before. The chance to forget a spell is independent of its level. Each day after the 5th that the spellcaster is unable to study their spell book, the spellcaster adds 5% to his chance of forgetting a spell. Spells that were learned and then forgotten in this manner needs to be relearned, but this in a different way than when the spellcaster first learns them. The spellcaster will always be able to relearn such a spell with a (i.e., chance of 100% - thus there is no chance that the spell will be forgotten forever unless a source, such as the characters spell book or a scroll, etc., cannot be acquired). 

Relearning a spell requires a total of 5 hours per spell level must be spent by the spellcaster to relearn a forgotten spell. These hours need not be spent consecutively, but a session of less than 2 hours will not count toward diminishing this time. No more than 10 hours per day can be devoted to relearning spells.