Moonshrine Sanctum is located within Blackfathom Deeps and is the high seat of the Twilight's Hammer cult of this area, led in ritual by Twilight Lord Kelris. The sanctum is an ancient temple devoted to Azshara and it appears that the Twilight's Hammer has no issue with the naga goddess, as the statue is kept in good condition.
Moonshrine Sanctum lies beyond Moonshrine Ruins and leads directly into Aku'mai's Lair, past a set of large double doors. To open the doors, all its guardians must be defeated by lighting the four candles around the statue of Azshara. It is advisable to light the candles one at a time, as each will spawn a group of sentries, either crabs, turtles, makrura, or water elementals.