Ok, so 1s and 2s it is.

Now, what can a sorcerer do? Anything? Or is he limited in knowledge?

Thinking about the classic elements in ancient Greece (and the number 4 of BoL), we have fire, earth, water and air. I think the sorcerer can manipulate the very essence of the element, but why not giving secondary powers, related, let's say, to the tarot view of them?

So...

Fire: manipulating fire, dealing with active movement, willpower, drive, motivation, passion.
Earth: manipulating earth and rock, dealing with physical health, luck (prosperity), fortitude, sexuality and appeal.
Water: manipulating water, dealing with emotions, intuition.
Air: manipulating winds, dealing with mental affairs, intelligence, thoughts.

But why stop there? We also have secondary elements:

Steam (Fire + Air): Illusions, spiritual (non-physical) world.
Lava (Fire + Earth): Physical undead, protection.
Ice (Water + Air): Controlling minds, limiting the flow of time (never reversing, never stopping).
Mud (Water + Earth): Adapting to harsh environmental conditions, resisting poison.

(of course this is just a first draft)

And we have two final elements (in theory at least; I don't know if I should include them):

Light and Darkness (Fire + Water or Air + Earth): they both deal with the supernatural nature of men, with their beliefs and creations, but in different aspects. By mastering the opposite elements a spark of the "whole" can be grasped.

The idea is a sorcerer has access to 1 element for each point on a Sorcerous Carreer of sorts, with the following limitations:
-The first two elements a Sorcerer can "tap" energies from are one of the 4 classic ones (fire, earth, water, air);
-When a Sorcerer knows two elements (and has enough Sorcerous Carreers), he can learn one of the secondary elements (steam, lava, ice, mud);
-Light and Darkness should be limited to very powerful Sorcerers, if they exist at all.

The GIT! wrote:

This is an interesting idea. I do have a concern taking this forward. In order to learn a secondary element, are you saying a sorcerer must have knowledge of the relevent classic elements? i.e. To learn Lava the sorcerer must first know Fire + Earth. If that is the case, then it is likley that the maximum career rank of 5 will be insufficient to gain more than one secondary element. That said, learning a secondary element without the correct classic elements just seems wrong. How about allowing a sorcerer to gain access to the secondary elements once he has knowledge of the suitable classic elements and, if a sorcerer has rank 5 in his career, he only gets to choose Light OR Darkness as his final element? 

The idea is to impose a limit on the Sorcerer's knowledge. I was even considering limiting the total elements known to 3 (including secondary ones), but that would be counter-intuitive when everything can be Career-based.

Example of Sorcerer's Path (this would be an extreme exemple, since all the hero's careers are devoted to sorcery):
Career 1 - learn Water
Career 2 - learn Earth
Career 3 - learn Mud
Career 4 - learn Air
Career 5 - learn Darkness

The GIT! wrote:

I could be wrong but I think you may be misinterpreting how careers work. A starting character has 4 careers and, with advancement points, can learn more careers during game-play. Each career has a ranking (maximum of 5) to represent the characters aptitude in that career.

I believe your example above really only represents one career with a rank of 5.

I just created an extreme example. I really doubt a player would devote all ranks (including an advancement) to a single career. Imagine a Boatsman 0, Mercenary 0, Slave 0, Sorcerer 4 starting hero... Feasible, but not practical, I believe.

Yet, there's the option to do so.

The GIT! wrote:

The question is whether you are wanting a sorcerer to have to chose a secondary element as a career rank? If so then it will really make things difficult as the limit of 5 ranks in a career will seriously inhibit the choices available. 

Consider this a feature, not a bug. I don't want a hero to know everything about magic--limiting the choices is intentional.

So, the only way to learn Light or Darkness is devote a whole life to it. This is how I imagine the great sorcerers of old, so this tries to emulate that.

The GIT! wrote:

I'm wondering if it might be better to make the choice of elements similar to chosing Boons. 

So you think the "basic" elements could be equal to the Sorcerer Career Rank and the secondary would become Boons you acquire later?

I think this could lead to fewer players choosing them. You can do a lot of stuff with the "basic"... In fact, one element can "emulate" the other in some sense (you can use Fire to heat something or use Water to dehydrate it), so making the secondary elements "expensive" may not work as intended.
 

The GIT! wrote:

You may be right but it's also unlikely anyone will choose them as they increase Ranks in their career for the same reason you mentioned. 

In other words, this needs more brainstorming. :-)

Of course this could work with any kind of magic fields of study, from the dozens of schools of magic you see in GURPS Magic, to the five colors of magic of Magic: the Gathering. If you really want, you could simply make a White Magic / Black Magic separation and this is good to go.

The most important part is the system, and it's working...

Now, how to determine the fields of magic? That's the next step on our journey.