It looked like a pendant with a jeweled bead. It enabled its user to detect and capture Odic energy. Varaxils "Lucern" and "Finicia" used it to find and capture individuals with Odic potential. As other Odic-based artefacts, its operation was more an art than a science. In addition, the WitchStar was highly unstable and prone to catastrophic failures in the proximity to Lokic fields.
When the two Varaxils crash-landed on Vetter's Tor, a mistake in the settings resulted in the deaths of five people, whose life force was completely drained. The essence of the victims was absorbed into the WitchStar, which enabled the Varaxils to use the memory of Lucern and Finicia Portillon, children of the village squire, to facilitate their search for Odically gifted humans.
John Kincaid's careless handling of the WitchStar snatched from the Varaxils led to the release of all Odic energy accumulated within and its absorption by Agnes Bates, making her impervious to the WitchStar.
Later, the WitchStar became the squire's possession. Without knowing its purpose or full potential, his descendants were passing it down the generations. 350 years later, "Lucern" and "Finicia" stole it back by forcing open a drawer in the study of Aleister Portillon.