Jewel of Karathoth

The jewel of Karathoth, which was also called Karathoth's jewel, was a powerful enchanted gemstone that was created by an incarnation of Thoth.

Description
The gemstone had between five and eight facets.

Powers
Karathoth's jewel could be used to create an exact duplicate of whoever held the jewel. The duplicate was under the complete control of the wielder for 40–70 minutes before vanishing. When a duplicate was killed or vanished, a single facet of the jewel would crack and could not be used again. The jewel of Karathoth became useless when all of the facets cracked. A single duplicate could be created at a time, and two days of waiting were required before the jewel could be used again.

Any magic items carried by the duplicate disappeared with them, but the effects of spells cast by them remained active upon their disappearance. Duplicates could not use creation magic or cast wish.