Inscribed Orb of Deliverance

From the description

His search led deep into the earth, down into ruins undisturbed by surface dwellers for millennia. Every scrap of evidence he'd found told him a greater, far older civilization had preceded those whose technologies he had already pilfered. But there were reasons no surface dwellers had come this far in ages, and Disruptor would need to modify his equipment with secrets found along the way just to ensure he might continue a bit further.