Players can take part in another post-game series of side quests called "Menace Beneath Lucis" in "Final Fantasy XV" by talking to Ezma at the Meldacia Hunter QC. However, you must finish the main story and complete certain dungeons.

According to IGN, to receive the Sealbreaker's key from Ezma, players must first defeat the final bosses within these dungeons: Daurell Caverns, Crestholm Channels, Balouve Mines, and Costlemark Tower.

Ezma's first quest in "Final Fantasy XV" is "A Menace Sleeps in Keycatrich" and is located at the Keycatrich Trench. Make sure you are level 55 or higher. The Keycatrich dungeon is easy to navigate, and you can just follow the path until you come across an intersection path thrice.

For the first intersection go left, then straight at the next one, then finally, go straight again to face the boss. The Flan has a lot of health, but it's similar to the smaller Flans. Don't forget to pick up the located in the room where you fight the Flan. The Dominator Greatsword, Wizard Shield and Hyper Magnum Handgun can also be found in this quest.

In the second "Final Fantasy XV" quest "A Menace Sleeps in the Grotto," gamers must be at least level 65. The secret dungeon is located in the Greyshire Glacial Grotto near Callatein's Plunge. Make sure you have fire magic and Polearms since many enemies in this dungeon are weak to them.

In the dungeon, you will enter three large rooms with multiple exits. Choose the door to the right of where you entered in the first room, then the one in the middle in the second, and the left in the third. Keep an eye out for the Vigilante Daggers and the Executioner Handgun. The final boss is a Kenga, a Ronin-type enemy with high health stats.

Ezma's third quest is "A Menace Sleeps in Fociaugh," located in the Fociaugh Hollow. Make sure you are at least level 65 before heading into the Malacchi Hills. Most of the enemies here are weak to Greatswords. In the first large room with multiple exits, the path straight ahead will lead you onwards, but don't forget to pick up The Grand Chamberlain, an Ignis-exclusive accessory in the path to the left.

You will see a camp site next along with the Organyx daggers. In the second room with multiple exits, the path right across the entrance has an Oracle Ascension Coin and the path to the right will take you deeper. The boss is a Chandravarma, a stronger version of a Red Giant. Use your Armiger and Royal Weapons to defeat it. Once you defeat the boss you can retrieve the Enhancer Greatsword.

For "A Menace Sleeps in Daurell," head to the Daurell Caverns. A level 72 or higher party is suggested along with bringing lots of Ethers and MP restoring items. Once you enter the dungeon, defeat two Pyromancers then take the left path. Once you are facing an Iron Giant and other enemies, make sure to leave at least once enemy alive so Noctis can Point Warp to the entrance if you haven't done so when you first entered the dungeon.

Watch out for Sir Tonberries. They are weak to all weapons. Use magic, Ignis' Libra Elementia, or the Ring of the Lucii against Custards and the Docles. 190 MP to kill them with the Death spell. In the first room with multiple exits, go left to continue to a camp site and a Moogle Charm. In the next room, choose the middle path and in the third intersection, choose the right path to proceed.

At the second campsite, get the Duel Code Greatsword. You will also face an Iseultalon, which is weak to Greatswords. The final boss is the Mahanaga. Similar to a Naragini, it weak to swords and lightning. Defeat it for Precision Lance.

The fifth "Final Fantasy XV" locked Dungeon quest is "A Menace Sleeps in Balouve," located in the Balouve Mines. With a level 78 party, go down to B4F. Return to where you first fought the Aramusha in an open area in the north-west section. Go up the stairs until you reach the ladders, then enter the narrow passage in the northern corner. Inside, the north path will lead to the secret dungeon.

The straightforward path is easy to navigate. Go left in rooms with multiple exits to continue. The campsite also has the Apocalypse Greatsword. Defeat the Pyromancer, then get the Death Penalty Handgun.

Bring a level 86 party for "A Menace Sleeps in Steyliff" in Steyliff Grove. The entrance will open only from hours 19 and 4. The dungeon will take longer to finish, so bring lots of items. Head to B1F then go north-west corner to the stairs that will lead you further.

In B3F, go up the staircase and follow the path. You're going the right way if you face two Reapers. Go down the stairs to return to where you fought the dungeon boss and unlock the door at the opposite end of the room from where you enter the boss fight area. In the first room with multiple exits, go straight ahead. Pick up the Celestriad accessory from the right path if you want.

After heading down several floors, you will see a second campsite. In the second room with multiple exits, go straight ahead from the entrance. In the fight against multiple Tomberries, use Ignis' Overwhelm or Gladio's Impulse. Defeat them, then get the Balmung Greatsword. After the campsite are several enemies. After the fourth campsite are more enemies and at the fifth campsite are Tonberries.

In the room full of Wyverns is the Aegis Shield followed by a campsite. In the third room with multiple doors, take the left path to continue. In the right path is a Noctis-exclusive item called Robe of the Lord. After the eight campsite is a room of Dolces which are only weak to magic.

After the next campsite are more Tonberries and a Master Tonberry. After the next campsite is the miniboss Griffon. The final boss is the Mictlantecihuatl. Use Polearms, Daggers, and Ice magic to defeat it. Don't forget the Flayer Polearm.

Bring a level 92 party for "A Menace Sleeps in Crestholm" in Crestholm Channels. The secret dungeon is close to where you fought Jormungand. Go north to find a ladder that leads down to the entrance of the secret dungeon. The dungeon has 30 floors and two campsites. In the first room with multiple exits, choose the right path to continue.

At the next room with multiple exits, go left to exit. After the campsite, is another room with multiple exits. Go straight to continue. After the Gaiatoad, choose the center path to exit the room with multiple exits.

Defeat a Phalaris, which is followed by the next campsite. After several enemies is the Manxom which can cause Petrification. You will receive a Gigas Bangle when you defeat it.

Bring a level 99 party for "A Menace Sleeps in Costlemark," located in Costlemark Tower which can only be entered at night. The dungeon has 60 floors can take at least two hours to complete. There are no enemies until the normal dungeon, but you cannot use items in the locked door dungeon.

At the room with the block puzzles, you can descend through the north-east corner of the room which will also contain the first enemy you will face. Once you reach the open lower floor, you will fight Flans and a Red Giant. On the same floor is a small hole in the western wall you can crawl through which leads to the secret dungeon's door.

Equip Ignis with The Grand Chamberlain accessory (found in the Fociaugh Hollow secret dungeon) since it lets Ignis heal Noctis his health falls below 50%. Try to unlock the healing Ascension nodes in the Recovery section of the Ascension skill trees so the party can heal themselves. Create Healcast spells so Noctis can heal himself.

Some floors have no enemies, and listed here are the floors with enemies: B2F: Hobgoblin x4, B8F: Oracle Ascension Coin, B10F: Haven, B11F: Goblin x5. In B12F are two Mindflayers, and the exit is across the entrance to the room.

B13F: Mindflayer x2, B14F: Hobgoblin x4; Oracle Ascension Coin, B15F: Goblin x5, B16F: Goblin x5, B17F: Hobgoblin x4, B18F: Hobgoblin x3; Onion Bangle, and B19F: Mindflayer x2.

B20F has a Haven, B21F: Hobgoblin x4, B22F: Malboro, BF23: Hobgoblin x3, B24F: Malboro x2, B25F: Hobgoblin x2, B26F: Hobgoblin x6; Gigas Bangle, Hypno Crown is at the center path, continue east, B27F: Hobgoblin x3, B28F: Jormungand; Soul of Thamasa, B29F: Hobgoblin x2.

B30F has another Haven, B31F: Braindrainer x2, B32F: Iron Giant x2, B33F: Braindrainer x2, B34F: Iron Giant x4, B35F: Goblin x4, B36F: Braindrainer x4; Oracle Ascension Coin (Right path); Exit (Left path), B37F: Goblin x6, B38F: Goblin x8; Applied Sorcery, B39F: Braindrainer x2.

B40F has a Haven and aPlatinum Ingot, B41F: Goblin x5, B42F: Uttu x2; Exit through the center path, B43F: Elder Coeurl, B44F: Uttu x2; Oracle Ascension Coin, B45F Uttu x2, B46F: Gobin x8, B47F: Gobin x6, B48F: Elder Coeurl x2, B49F: Goblin x3.

B50F has the final Haven, B51F: Uttu, B52F: Goblin x4; Oracle Ascension Coin, B53F: Goblin x3, B54F: Uttu x2, B55F: Goblin x2, B56F: Serpentess x2, B57F: Goblin x4, B58F: Serpentess x2, B59F: Uttu x2.

B60F has the final boss Bilröt which is weak to Daggers and Ice. Use Prompto's Piercer to lower its defense and have Ignis use either Enhance or Overwhelm.