Nephthys

Nephthys was the sister and wife of Sutekh. While her husband was trapped in a pyramid on Earth by the Eye of Horus, her mind was split up into two parts: her instinct which was stored in a woman who was mummified alive, and her reasoning in a canoptic jar. The reason for this punishment was that she was judged more dangerous than even Sutekh. (MA: The Sands of Time)

In Egyptian mythology, Nephthys was one of the Egyptian goddesses, a guardian over the dead, alongside Isis, who guards the canoptic jar containing the lungs.

Release
Her reasoning was released in 2000 BCE when robbers were plundering her pyramid and broke the canoptic jar it was stored in. (MA:The Sands of Time)