Skywalker said:
Cheers. That does help alot, especially for the standard classes like Gun Mage and Arcane Mechanik.
How does a Wizard get Magic Aptitude? Is it a feat with prerequisites or a class ability?
For prestige classes, boiling the problem down to its most simple, is there any way to say that some PrCs when taken can be counted as Wizard class levels for the purpose of determining Magic Aptitude?
For example, a Priest has Fighter 7/Wizard 3. He then takes Battle Chaplain 3. His total levels for determining Magic Aptitude should be about that of a 6th level Wizard. However, he is unable to take specific Magic Feats available to a Wizard during this period. Would this kind of thing work?
There are a couple of ways to approach it. Old One, above, is approaching it as a feat-based acquisition (Talent-based, actually, as he is using Grim Tales.

) In other words, once your character gets X ranks of Magic Use skill, they could pick up orders of magnitude. If you do this, someone should be picking up 1st mag at 7 or 8 ranks (about 5th level), 2nd mag at 13 or 14 ranks, and 3rd mag at 19 or 20 ranks.
Black Company ties magnitude strictly to Wizard Level - 4th class level for 1st magnitude, 10th class level for 2nd Mag, and 16th for 3rd Mag. If you do similar (that is, make magnitude a class ability, use the levels I wrote above as the minimums of caster ability at which someone gets first mag. So, let's have a prestige class that is very magically inclined as a wizard or cleric - if they are, you can tie orders of magnitude respectively to 5th and 10th level, since the fastest most people gain a given Prestige Class is 5th or 6th.
If you have a class that is not very magically inclined, they might reach only ONE increment. The important thing is to plan that someone is going to reach it the FASTEST they possibly can, and balance it that way. You wouldn't want 10th level people running around with 3rd magnitude, so keep those levels in Mind (pure caster 4th, 10th, and 16th) when balancing it out.