The Devil's Heart

The Devil’s Heart is the title of a 1993 non-canon Star Trek: The Next Generation novel by Carmen Carter, and the name of a legendary object of unsurpassed power and mystery which appears in that novel.

[1] The novel primarily explores the consequences of Captain Jean-Luc Picard's possession of—and near-possession by—a legendary object of power.

The Heart was later possessed by the Iconian people until their home world was destroyed 200,000 years ago.

It also figured in early Vulcan history - Surak's family had possession of the Heart until it was taken by a rival clan.

This resulted in a deadly race in which each species that had held the stone before attempted to reacquire the artifact.