Glenn's Eberron Campaign
Cursed Ring rod and cape that very temporarily enhance your mental capacity
These artifacts were first crafted by an ogre mage to help him craft his dream fortress. They flooded him with amazing visions of his fantastic castle, but before he came even close to finishing it, he was driven mad by the extreme visions and his obsession. He later killed himself after writing mad ravings with his own blood and locking up all of his workers. His failure became known as the “Cenobian Ruins.”
The PCs uncovered the rod, ring and cape from his tomb in hopes they can use the temporary power to fend off the forces of Ghularak, although what the artifact actually does is unclear still.