Researching Original Spells
If you decide to allow characters to develop original spells, you
can use these guidelines to handle the situation.
A spellcaster of any kind can create a new spell. The research to
do this requires access to a well-stocked library, typically in a large
city or metropolis. Research requires an expenditure of 1,000 gp
per week and takes one week per level of the spell. This money
goes into fees, consultants, material component experimentation,
and other miscellaneous expenditures. At the end of that time, the
character makes a Spellcraft check (DC 10 + spell level). If that roll
succeeds, the character learns the new spell if her research produced
a viable spell. If the roll fails, the character must go through
the research process again if she wants to keep trying.
A viable spell is one that you allow into the game. Don’t tell the
player whether you think the spell is viable when research begins.
(That’s the point of the research.) However, feel free to work with
the player before the research begins and give him guidance on the
parameters under which an original spell might be acceptable in
your game.
Research to create new spells is always in addition to any other
research involved for gaining spells that are already part of your
campaign (if you decide to also require spell research for the new
spells that casters are entitled to as they attain higher levels).
The number of spells that sorcerers and bards can know is
strictly limited; members of those classes can never exceed these
limits even through the research of original spells.