Counting Lil' Tarecgosa isn't a good idea if you're trying to have this guide work for as many people as possible.
I think it worth mentioning that a player must choose Filling the Moonwell to unlock Into the Depths, which starts the quest chain to kill Leyara (and earn Legacy of Leyara). Once that quest chain is completed, the quest chain that rewards Leyara's Locket is unlocked through a mailed letter to the player.