The Unending Dungeon

A Hidden Dungeons, which seems to be unique to people with the skill Great Sage. In addition to locating the entrance, you need to push the rotating wall on the left to reveal the stairs to a massive iron gate. No matter what kind of magic attack one summoned, it didn't seem like it'd budge in the least. It is also necessary to recite the required spell: "「The Hidden Dungeon only I can enter. Secretly becoming world strongest!」".