Skyfire is a type of stone that makes up the Orb in the Sky. If a dragon is holding or wearing it, telepathic NightWings won't be able to read their minds, hearing a low humming noise instead. If a telepathic NightWing is holding it, they won't be able to read minds at all.
The Jade Mountain Prophecy
Turtle said that he found a large piece of skyfire that fell into the ocean while he was swimming. Some small pieces broke off of it and Turtle had them placed into a golden armband. Towards the end of the book, Moonwatcher asked Turtle to remove some of the pieces and give them to Qibli and Kinkajou as a gift so that they could keep their thoughts private.
Moon told Turtle to give Winter one of the rocks so that it could shield Winter's thoughts as well.
While Anemone is casting a spell on Kinkajou's skyfire to heal her injuries and make her love Turtle as much as he loved her, Turtle cast a spell on it at the same time to protect Kinkajou from Darkstalker.
Later, Turtle gives Anemone skyfire to protect her from Darkstalker's telepathy.
- The rock appears to have an "evil sense," as described by Moonwatcher.