Golden Sphere of Seti
The Golden Sphere of Seti was a magical artifact that featured in ThunderCats.
This magical golden sphere enticed those that saw it to possess it upon which they became obsessed with the artifact. Their greed and ambition meant that they would do anything to get it after which they became more evil - turning even good characters down an evil path.
Mumm-Ra stated that his position of the sphere would have made him four times more evil and thus powerful then he was ordinarily.