"Okay so there were these wizards... uh I'm not sure how many of them were there, thirteen maybe? But they were trying to create a paradise. An everlasting utopia composed of all the good in the world. So they all gathered together in one spot and together cast a spell that would make their thoughts into reality.
The plan was that they would all in unison, think about all the good and holy things that they could think of, and pour it into the site they had chosen. However, there was a slight problem. You see, one of the wizards was evil. Corrupted by some unknown force, he instead focuses his mind into producing all the worlds evil. And as it turns out, one bad ingredient spoils the dish or something like that.
At first the place looked okay, so pretty much everyone in the surrounding countries moved there their. Or at least tried to visit in a pilgrimage. But then, after they enter, they came out. Once the paradise had reached maximum capacity, the corruption spread. It consumed the entire place, nothing was left untouched, turning it into a labyrinth of darkness. Then it got worse.
It just so happened that there were a few passing multidimensional universe hopping eldricht abominations nearbye when the event happened, and somehow they all got pulled in and bound to the labyrinth. I know that one of them got fused with one of the wizards, turning him into a insane incredibly powerful monster. But anyways, this granted the labyrinth's outer layers the strange property which caused them to be made out of constantly changing rooms that were pulled in from various locations across time space and dimensions.
Also somewhere along the way, it obtained some sort of hivemind sentience. Nobodies quite sure of what it's true nature is now, as overtime the distortion grew and the corruption continues to grow stronger.
As for the people inside... the less said about what happened to them, the better. Kaladar was one of the wizards who helped create the basement, and the only person who managed to avoid being corrupted by the subbasement's power.
So yeah, that's the story. I'm surprised you forgot it Fniff, you were the one who told me it after all."