When One Resource References Another

[SodiumTelluride]

If one legal character option references something in a different book, do I have to own both resources in order to use it? For example, if I own Ultimate Magic but not the APG, can I still play a hexcrafter magus?

[Cyrad]

I would say "yes" because the rules text for any content you have needs to be available to you and the GM for reference. If you play a hexcrafter, you will need the source for any hex you select.

[Starglim]

You need one rules source for how the ability works and the other source for rules allowing you to take it. A GM might need to consult either of these.

[Ascalaphus]

Yes, you need the books for all the rules you're using.

A hexcrafter is a magus (so you need Ultimate Magic). If you decide to take any hexes, you would need APG (for the general rules on hexes), and if you want to take a hex that's not from the APG itself you would also need the book with that hex in it.