[Endoperez]

First, 10% random means that about one in ten mages of that type are going to be more powerful in magic. The paths available from a random depend on the mage, and there may even be multiple randoms with multiple chances. Arcoscephale Mystics, as an example, have Astral 1, always one of Fire, Water, Earth and Astral (100% chance), and 50% chance in each of Water, Earth and Astral.

S
100% FWES
50% F
50% W
50% E

Or, maximum of 2 in each of the four paths, often only 1 in two, perhaps three paths, and in theory a lucky Mystic could even get 5 picks in magic.