Magic-User Spell Book (Part 3)

[Continued from Magic-User Spell Books (Part 1), which deals with the drawback of spell books in B/X D&D and Magic-User Spell Books (Part 2), which presents a possible solution to those drawbacks.]

Magical research. A part of the game I always wish was more commonly taken advantage of. Sigh. Anyway, I promised a little more comprehensive rules for spell creation in B/X D&D, and here I am to deliver.

For me, there are five main factors in spell creation: quality of the research facility (usually a library), level of the magic-user, intelligence of the magic-user, level of the spell, and what spells the magic-user already knows.

Research Facility: A library, laboratory, or some other type of research facility is necessary to conduct magical research and develop a new spell. The amount of knowledge and the quality of apparatuses available determine the base chance of success. An independent magic-user's library typically gives a base chance between 10%-30% (5% per 25,000 gp spent on books and apparatuses), the local Mage's Guild library gives a base chance of 40%; the greatest library in the kingdom gives a base chance of 50%; the most extensive library on the continent gives a base chance of 60%. the best library in the world gives a base chance of 70%. If the library is located in a dungeon, 30% + 5% per dungeon level usually works out about right.

Level of the Magic-User: The magic-user's has a +5% chance per level of the magic-user or elf.

Intelligence: Add (or subtract) the magic-user's prime requisite bonus to experience points.

Level of the Spell: Subtract 10% per level of the spell being researched. 

Read Magic and Read Languages: Add +10% if the magic-user casts either Read Magic or Read Languages. Add +20% if both are cast.

Thus a second level magic-user with an intelligence of 13 in the local Mage's Guild Library with the read magic spell has a 55% to research a new first level spell. The same magic-use would have instead a 85% chance of researching such a spell with access to the greatest library in the world.

Cost and Time: The cost remains 1000 gp per spell level. Because of the typically increased chance of failure, the time requires is reduced to 1 week per attempt.