Image: Rebel Wolves / Bandai NamcoOfficial screenshot from Rebel Wolves / Bandai Namco.
Mastery is earned by maxing out a single ability in the Swordmastery, Witchcraft or Vampirism tree. Most players get it by focusing on a favourite skill.
Pick one ability in any tree and keep upgrading it until it reaches its highest rank. The trophy pops at max rank.
Choose an ability you already lean on so the points are not wasted. Manuals for Swordmastery and magic help you level faster.