Inland and far from the sea, Astan City is one of the few places where players can hunt gillmen, and this underground water area can produce three types of expensive magical materials.

The gillmen's webbed feet are the best material for the "Underwater Speed" enchantment, which can increase swimming speed by 35%. The scale on their forehead is a casting material for "Tidal Wave." The second-to-last vertebra on their degenerated tailbone is the most valuable, being the strongest water affinity transformation material for those below level 50.

Even Felix's ancestral sword, "Gem Firework," owes its shaping properties to the fire-type creature corresponding to gillmen, the 'Flame Salamander Man.'

For example, if you have enough materials and grind 20 tailbones into powder, you can create a similar "Gem Water Splash."