Leviathan
Sailing north toward the Mysidian Tower triggers a cutscene that swallows your ship. This is a one-time dungeon. This chapter covers Leviathan for 5 missable chests and 4 new bestiary entries (3 missable).
Sailing into Leviathan
From the Cave of Mysidia, sail north toward the Mysidian Tower. A cutscene triggers when you get close; there’s no way to avoid it.
Inside Leviathan
The dungeon is a linear three-floor stretch with constant stomach acid (orange liquid) on every floor that deals 1 HP per step to each character. Not dangerous individually but it adds up over the run, so keep moving.
New Enemies (*Missable)
Bolt Fish (540 HP) and Manta Rays (870 HP, weak Lightning) handle the early floors, hitting 4-5 times per turn. Bolt Fish also casts Thunderbolt at you. Sea Dragons (870 HP, weak Lightning) appear later and add Tsunami for party-wide water damage. Thunder is effective against Manta and Sea Dragon and isn’t resisted by Bolt Fish, so it’s the obvious answer. Keep HP topped between fights since the acid chips you too.
1F. The dungeon is completely linear. Go west through the acid and follow the path. The Twist Headband sits along the way. Continue through more acid to the Power Sash near the exit, then take the door to the next floor.
2F. No random encounters on this floor. Walk north through the acid pool and west to find Ricard, a Dragoon. Show him the Crystal Rod and he joins your party. Equip him with whatever spare gear you have; he comes with decent starter equipment but can take your old Leila kit. Just north of where he was standing, grab the Power Armlet, then continue to the top-left exit.
3F. The Gaia Blade is at the top of the map and a strong physical-attacker upgrade. The Diamond Shield is on the south side, the only monster chest of the dungeon. 5 Red Souls ambush it; Holy is effective against them, and the shield is worth it. Once both chests are clear, walk to the middle-left of the room for the boss.
How to Beat Roundworm
After the fight, board the ship. Ricard stays as your fourth member. The next chapter heads to the Mysidian Tower. The Crystal Rod opens the entrance and the Ultima Tome waits at the top. The tower is the longest dungeon yet at 10 floors; stock Ethers and make sure your healing magic is well-leveled.