The route from Beartzun is long but it's nice. I climbed across the route of dolmens. It's a nice path climbing Urrixka (990m) and Argañeta (1008m). The ridge follows reaching the small summit of Burdingurutx before the peak Antatxula or Antxola (1119m) after 3h 30 minutes. In this point it require 45 minutes more to summit of Auza in a easy path but I left the route because I was necessary return to my house to have lunch (I was a little lazy in the morning).
I had the information to write the route in the next weeks but I don't climb the summit in this time.