Just throwing this concept out here

[alexti]

I think that it may be more interesting to counter-position national/non-national magic paths rather than some predetermined pairs. Basically, national magic paths would be cheaper for pretender and other paths more expensive. Thus, for example, for Vanheim air magic on pretender would cost significantly less than fire magic. This would help to keep national magic more different in the late game by making it more expensive to get into other paths through pretender...