IMPORTANT: Before we go any further, I want to you check missible bestiary below because they will be inaccessible after you clear the Mysidian Tower.

It's also a good idea to save your game in another slot.

Open your Inventory -> Configuration -> Bestiary and confirm the following monsters:

• 011: Phorusracos - Around Dreadnought area.
• 031: Antlion - East desert.
• 040: Killer Fish - Outer ocean.
• 042: Helldiver - Inner ocean, west ocean.
• 045: Buccaneer - Inner and outer oceans.
• 052: Sea Snake - Oceans.
• 054: Land Ray - Grassland, south and north of east desert.

Once you confirmed you got all these monsters in your bestiary. 

Proceed to the Mysidian Tower.