Rokugan D20 question

[Talya]

The Void Use feat says a character who takes it starts with 2 void points, but they have the potential to gain more. I can find no mechanic by which a character's number of void points can be improved. What am I missing?

[Geddoe]

The Depths of the Void feat at the bottom of page 49 in the same book.

Edit: Edited to not seem to be as big a douche.