If you didn’t catch the dev stream about the new mount and the masteries tied to it (here’s a shorter clip detailing the masteries), it will require 12 total Path of Fire mastery points to complete (the first mastery needs three mastery points, the second needs 4, and the third and final needs 5).
I personally was anticipating it requiring only six, as the previous mastery needed five, so just a heads-up if you’re running low on PoF mastery points!