Bilgen is an area within the West Underworld region and contains 5 zones.
| Zone 1 | ||
|---|---|---|
 | ||
 Clockwork Mole |
 Dwarven Engineer |
 Dwarven Overseer |
 Slime |
 Carrion Creeper |
 Coin Creep |
 Dwarven Steamdozer |
||
| Zone 2 | ||
|---|---|---|
 | ||
| Clockwork Mole |
Dwarven Engineer |
Dwarven Overseer |
| Slime |
Carrion Creeper |
 Clockwork Blesmol |
| Coin Creep |
Dwarven Steamdozer |
|
| Zone 3 | ||
|---|---|---|
 | ||
| Boss battle against | ||
| Clockwork Mole |
 Dwarven Axeman |
Dwarven Engineer |
| Dwarven Overseer |
Slime |
Carrion Creeper |
| Clockwork Blesmol |
Coin Creep |
Dwarven Steamdozer |
| Zone 4 | ||
|---|---|---|
 | ||
| Clockwork Mole |
Dwarven Axeman |
Dwarven Engineer |
| Dwarven Overseer |
 Dwarven Warrior |
Carrion Creeper |
| Clockwork Blesmol |
Coin Creep |
Dwarven Steamdozer |
| Zone 5 | ||
|---|---|---|
 | ||
| After completing this Zone you get the 4-Rear Formation. | ||
| Clockwork Mole |
Dwarven Axeman |
Dwarven Engineer |
| Dwarven Overseer |
Dwarven Warrior |
Clockwork Blesmol |
| Dwarven Steamdozer |
||