Key of Knowledge

It can unlock the mysteries binding the truth of the world and grants knowledge beyond the understanding of humans.
No matter how the wielder attempts to display their possession of the key, no one but themselves can see its form. Some people believe that to be a gift from the heavens, while others think it's a sign of mental disorder.

"I had a dream of molecules coiling up into a loop like a snake biting its own tail. I woke up realizing that this is the answer I've been looking for all along!"