You can find this on Yder cave (west area). You need to trigger an event to find this hellion, visit THIS PAGE for more info about it.
It’s located on the northwest area where there is a dead end (see the video for exact location). You need to have Stealthy Feet (rose’s support talent) to engage this one; My proficiency for this skill is 16, if you can’t fight it then it means you need to raise the skill proficiency more.
Recommended Level: 30-35
Recommended time frame: After defeating medusa
Property: Amorphous, Dragon
The battle is easy, the dirt leech is small and quick, I suggest you to armatize with Lailah because the sweeping attack is very effective (easy to hit it).