The Headmaster Title – Secret Title

The Headmaster / Headmistress Title is a character-bound hidden title added in the Legion expansion. You can permanently unlock the title by completing an Archaeology quest chain.

The quest chain is relatively short and starts off with the quest Academic Exploration in Dalaran. Tae'thelan Bloodwatcher hands out the next quest and can be found in Azsuna, east from the Illidari Strand.

/way Azsuna 47.5, 42.5

Upon completing the quest chain, you will be awarded with a Key to Nar'thalas Academy.

Using this item in the Hall of Arcane Learning will transport you to a time-warped version of the room where you can do more mini-games such as more rune drawing and picture fighting. Here you will also find Elya Azuremoon who you may duel after completing all the activities (although some speculate that you can simply walk up to her and duel her).

Challenge her to a duel, and if you defeat her, your character (and any others who were in a party with you) will obtain the Headmaster/Headmistress title for their character.