This is easy.

Say a Pyromancer finds a scroll with the Magician form of Fireball.  He still has to make a roll based on his INT to find if he can learn the spell, correct?  Fine.  Since it is in a different form/from a different school/otherwise somewhat foreign, I would rule he takes a -50% penalty on the roll.  That means if the poor sap has an INT between 9 and 12, he has 0% chance of learning it.  A Pyromancer with an INT of 18, would have a 45% chance of learning it, etc...


TANGENT ALERT:
In my Blackhawk project, I'm breaking magic up even further.  There are Traditions of magic, notably Eastern and Western, then there are actual schools of magic, as in, actual places Magicians etc.., are taught how to cast spells. 

The Eastern Tradition is centered around altering the mind.  It's your Illusions, Charms, ESP, Suggest, etc..., and the great seat of power of Eastern Magic is centered in the Great Kingdom, where court intrigue, influence, diplomacy, and subtrefuge are the order of the day.  The Eastern tradition has a strain of summoning (demons) and espionage as well: darkness/light, silence, knock, etc...  It's all stuff developed to deceive/influence/control others.

The Western Tradition is centered on physical and elemental magic: fireball, web, summon elementals, etc...  It's seat of power is in the area of Ull, the Paynims, etc....

Actual schools teach things differently. So, if you are a Pyromancer, who studied at the Khalif's Madrasa of Smoke and Flame in Ekbir, and you find a Fireball scroll written by a disciple of the Grand Vizier's College of the Arcane Arts in Zeif, you're going to suffer a 15% penalty.

In a similar vein, an Eastern Magician who learnt magic in Nyrond is going to have a 50% penalty when trying to learn the same fireball spell written by someone of the Western Tradition, if it is even on his list (and it may not be in my game....still fiddling)

Of course, a Cryomancer trying to learn that spell is SOL.

Those in the central states, Greyhawk, Furyondy, Dyvers, tend to have a blend of both Traditions, and suffer somewhat less penalties.  BUT, the schools are incredibly exclusive and the washout rates are high.
 

Last edited by francisca (1/14/2016 11:48 am)

Ghul wrote:

That's an elegant solution, Rich. Something like that could function as an option, without changing the original rule, which is something (in general) I'm reluctant to do. I like it!

Of course, it's purely a houserule.  I'm just trying to point out it doesn't have to be all that complicated when you can leverage an already-existing mechanic.