Core Q&A Expanded Answer
Síol-Radharc, meaning Sight-Seed, is a Tuatha relic created when Badb Catha etches a new Tuatha Time Magic sigil into Livie's staff. The sigil allows Livie to use her intent to find the Time-Threads relevant to a specific person, event, or proposed action. She can then discard irrelevant threads and examine those that could affect Breanna's timeline.