Orb of Cassia (3.5e Equipment)
From D&D Wiki
This round orb (20 centimeters in diameter) belongs to Cassia, a deity of decadence. She uses this nigh-indestructible orb to store excess emotional power that her body cannot absorb from her followers. Cassia is very protective of the orb, as it can give her a power boost when she needs it and can be used to replenish her powers for a time if her followers should be stopped from worshiping her for some reason. She keeps the orb in the most well-protected room in her palace and she never lets anyone else see it. Even seeing it for a split-second is enough for Cassia to smite you dead, no matter who you are or what your relationship to her is. Since Cassia has never told anyone about it, the orb's existence has been detected through the most advanced scrying techniques. If the existence of her orb is even mentioned to her, she will use an enslavement spell on the one who mentions it, ask how he knew about the orb, then kill him. The power contained in the orb is great, and can be used to replicate spells of all power levels.
When it is empty, the orb appears to be white, but the fuller it becomes, the darker it gets until it is pitch black when it is nearly full. Cassia has never had the orb up to full capacity, and she sometimes uses some of that power for her own insidious ends, such as breaking through to locked planes, or creating terrible natural disasters.
Mortals who use the Orb do not know how to use it efficiently, and the only one who truly can use its full power is Cassia herself. A great amount of power is expended every time a mortal uses the orb; most of that power is wasted in the process of utilizing the artifact.