Soldier Dius:
First of all, Dius did not willingly succumb to the Seed of Destruction. As a result, he becomes stronger whenever the Seed becomes weaker. Unless the Seed of Destruction becomes stable, therefore, you can't defeat him.
Even then, you can't you can't destroy Dius by normal methods. He has an acute sense of smell and is very intelligent, so he rarely appears when there are a lot of people present. Instead he strikes isolated individuals when they least expect it.
But he can be defeated! You just have to lay a trap for him! When Admiral Keucereus ordered me to destroy Dius, I spent months perfecting a trap.
First, we need flesh from one of its subordinates: the Drak, Drake Wing or mutant Drake Wing. Collect 100 Drake's Flesh. I need that much to prepare a single trap. Later I'll explain it more fully.