The mysterious underground locations have a ‘long-standing” connection to the Tantas. While they are full of enemies, you can also find valuable equipment inside them.
The reward for completing Locked Labyrinth: East is a wearable Necklace, but you will have to encounter a boss at the end of this dungeon for it. If you find yourself unprepared, you can always open the start menu and choose to quit this quest, in order to return to the Labyrinth’s entrance above ground.
Once you are inside, head straight down the passageway and open the first door. In this room you’ll encounter four Abyssal Boggarts and three Abyssal Breakzombies. The zombies are pretty slow, and like Cuff’s analysis says, just don’t let the Abyssal Boggarts get hits in behind you, and you will be fine. Make sure you dodge their projectiles. The two left-hand corners of the walls will have Healing Draughts on the ground for you.
Open the second door and there are two pillars of Mana on both corners nearest you in this room (and the next). You’ll see a statue you can interact with in here that will allow you to return to the entrance, if you would like. Open the door to the next room.
An Abyssal Chaplania, two Abyssal Limnocyons are waiting for you. Cast Bind on the Abyssal Chaplania to help you out.The bear-like creature will have the largest health pool, so Burst Shot will be of use here to take him down. The Abyssal Limnocyons are immune to being tangled with Bind.
Open the next door, and there will be some firewood and another statue to touch to return to the entrance. The next door leads to a large open area with water and icebergs to stand on with a boss fight. The door you came through will be locked, once you enter.
The area you fight the boss named Lesser Deinosuchus will make you unable to land your Genesis spell because the boss is completely within the water, and your attack can’t reach, even with upgraded spell levels. You don’t want to be in the water near this boss. If you fall, swim faster in the water and then use magic to jump back onto an iceberg. The Deinosuchus will throw circular razor discs at you that you will want to vertically jump over through parkour. Three Geysers will also target you, when the boss attacks. Dodge to the side or sprint. You can hit the boss on solid footing with Scatter Shot’s reach, but if you want to do better damage, you will need to hop on the icebergs to land a Burst Shot spell.
If you lose the boss when it submerges, use Cuff Scan to find its next location in the water. The Lesser Deinosuchus will cloak itself in steam before disappearing. Cuff Scan will also reveal a Healing Draught further on the right-hand icebergs, behind a pillar on the right, around the door you came in from, and on a wall hugging the left-hand side, about mid-way from the next door you have to go through. If you have the Tendril spell, use it to regain some health as well.
If the boss is giving you too much trouble, turn on Auto Evasion, and Frey will automatically dodge the disc projectiles launching at you, as well as the geysers. Then you can just focus on landing your hits with either Burst Shot or Scatter Shot. Changing the difficulty before the boss fight is also an option because you can’t change your difficulty setting during battle. While the difficulty mode can’t be changed, you can adjust your Aim Assist, Damage Received, and Stamina Recovery Speed as options to help you, if you would like.
After you defeat the boss, go through the next two doors. You will enter a well-lit room with seven pillars of Mana and a huge golden ball-like artifact to go interact with in the center. You will gain the Archive Entry called Ancient Altar: Inscription 1 in the History of Athia section.
Your reward will be the Orison Necklace that triggers an auto-heal effect whenever an enemy is defeated.