Among the swords of justice, Terrakion is seen as the protector of Unova's caves and mountains. Many have mistaken this for an easy task, and it is true that today Terrakion has the lightest workload of the group, but this has not always been true Human expansion has only modestly touched Twist Mountain, Reversal Mountain, and Unova's numerous caves – and always in a kind, environmentally sensitive manner – not because of lack of effort, but because Terrakion is very good at its job.

There have been times in Unova's history when humans attempted to treat Terrakion's sphere like any other wilderness, and gave no thought to the consequences of their actions on the local pokemon. Techniques such as mountaintop removal offered far greater profit margins for mines, and had been used profitably in much of the world, but those who attempted the same in Unova soon found themselves standing under the wrong end of Terrakion's hoof-like boot. Time and time again Man failed to conquer Terrakion's realm, until he gave up and accepted admittance on the sword of justice's terms.

But the struggles over the caves and mountains might are all but forgotten today, when humans have accepted that they venture into certain lands only as guests of a watchful, rocky god of justice. At times, when faced with abusive bosses or when disadvantaged by a rival's underhanded scheme, the miners of Twist Mountain have even gone so far as to call on Terrakion for protection – and unlike its comrades, Terrakion has proved willing to defend innocent humans as well as pokemon from both petty and grand tyrannies. Indeed, while human ingenuity makes them far more able to exploit and destroy others on average, there are pokemon who can threaten innocent humans, and Terrakion does not hesitate to strike them down.