Dungeon Eternium

Dungeon Eternium is the SSS-Rank Dungeon who lived around the north pole and is the progenitor of the Wisps. He is the direct enemy of Xenocide, and his Mana has an effect that somehow makes it so that you don't notice certain potentially worrying things. He was in possession of a Silverwood tree when Cal found him and, after Cal bonded with his own, was able to use it to incarnate fully in Cal's Soul Realm. His exact motives are unknown, and he has given no reason for his desire to enter the soul realm other than that the moon was falling on him, which brings up the question of what was keeping him from simply retracting his dungeon territory and going somewhere that it wasn't falling, but there has been no answer for that in the books.