Disasters
"This realm is being absorbed by the Origin realm, I've told you that much. But the source of this realm seems to have manifested in the form of that tower. Basically, that is where the laws of that realm are the strongest, almost making it like an entire realm altogether. For you to find it using your senses would require you to have senses that could transcend the boundaries between realms. Even for you, that would be a bit much.
"That is also one of the reasons why the purpose of this final trial is to clear a floor in the tower. For every floor you clear, a bit of its power gets used up, and it becomes easier for the Origin realm to absorb this realm. If you somehow manage to clear the whole tower, then not only will you gain a tremendous reward, but a massive amount of energy will be used up."