Execute the Executioner (Hidden achievement)
The executioner event you’re trying to do only happens if the White Mantle take Saidra’s Haven (which only happens if the defense for that area fails). But they changed that achievement the other night:
“Renamed the Execute the Executioner achievement to Perfect Execution. This achievement now requires players to complete either the “Defeat the White Mantle and save the villager from burning event” or the “Escort the quaggan refugees to their destinations” event in order to obtain it.”