Revenge
The Elves brought Aeon to ride behind his horse. They moved through the forest and roads that were littered with corpses.
Aeon just stared flatly. These monsters are so weird and he had never seen them in his entire life. They are creatures that come from a completely different place.
But he's not afraid or even worried. He somehow had a hunch that he had some kind of connection with these monsters. It didn't take long for Aeon to figure out that the creature who had encountered him using his form, who was also the one who freed him, was the mastermind behind these monsters appearance.
The Elves who accompanied him told him about what happened in this world. Suddenly, out of nowhere, these monsters appeared. At the same time, a kind of plague or dark magic emerged which turned the Elves into undead.