What once existed is now shards of reality, floating in the sea of conflict...
The Truth Mage, Veracit, feared to utilize the Observer's Paradox, uncomfortable with their perilous effect on reality.
It's so cute!
Wait, why is it glowing?
A magical pair of glasses once allowed the sharpest of minds to perceive the physical world around him. His cutting insight, throwing light on the darkest of secrets, is now housed within the spectacles.
The Yugzhee, or "hedgehog-people", guard a great, secret treasure inside their giant burrowed lair. The mysterious Wall of Keys, a 12'x10', foot-thick, cold-iron, "wall", upon which, on iron hooks, hang 100 ornate iron keys of all shapes and sizes. Each key opens some heretofore un-openable barrier, door, or gate, in the particular game world of choice.
The PCs have come upon a great boon, except for the fact that the keys cease to function properly if separated from the iron wall for more than a few minutes. Higher level characters will be able to figure out how to take the wall "with them" via magic. Lower level characters will have to get creative.