My Favourite Chaotic Eldritch Horror

The Report on The Phenomenon

Deep within the depth of the spiraling mix of caves, there is something lurking beneath the stone caves. Even deeper than the abandoned stronghold. Nobody who finds it is ever looking for it, yet they find it all the same. There is a single door that had been carved out of stone, that is out of place of the apparent dead end cave. Opening it reveals what seems to be the surface. But something feels off about it, but everything looks exactly how it should, and that in itself is worrying, considering how you find this mysterious place. Most people report nothing else out of the ordinary, and they just leave the way they came. But once they return, the door has returned to normal stone.

But there has been one report of something different. The last report of this phenomenon. They said they wandered for a long time, and came across a figure standing in a field of flowers. The figure turned, and they had a red glowing eye, and long red horns. The figure approached, but the person who made this report was so scared, they couldn't recall the person's features. The figured grabbed their shoulders, and whispered in a voice that sounded completely unnatural, as if multiple people were speaking at the same time:

"You shouldn't be here much longer. Soon you'll forget how to leave."

The person then regained consciousness outside where the door once was, but it had reverted back to stone, but this one time was different. The stone had been smashed in.
Every other report since then has found the cave, with the smashed stone wall. No matter how hard you try, people say that stone is unbreakable.

Nobody knows what caused the phenomenon, and nobody knows where that... thing is now. It could've been just a figment of that person's imagination, but after that person's experience, people who had previously encountered the phenomenon have reported seeing a figure that whispers inaudible words, in a voice that is exactly how the last report said the figure behind the stone door said it spoke.

As far as we know, it can't be human, and God help us if it decides to be an enemy of humanity, because if can create a world exactly like our own, and destroy it, God only knows what it could do to us.