Reincarnated into a World Filled with Dungeons, But My Blessing Turned Out to Be the Most Challenging Dungeon

Summary

At the age of 15, a boy named Eric underwent a blessing ceremony and was granted the unimpressive ability to create a small alternate dimension. However, this was actually the most powerful skill, "The World," which allows him to create his own dungeon! Now, Eric, use your abilities and knowledge from your previous life to obtain the magic core and conquer all the dungeons!