Item from Crescent City by Sarah J. Maas
An ancient artifact now fused into Bryce's body — the other half of the weapon system that can unmake the Asteri's empire, hidden in plain sight as a tattoo between her shoulder blades.
The Horn is the Asteri's greatest fear and Midgard's only real hope. Paired with the Starsword, it can open portals between worlds — which means it can let the Princes of Hel through, or it can seal the Asteri out of Midgard permanently. Micah killed Danika and the Pack of Devils trying to find it. The Asteri have been hunting it for millennia. Fused into Bryce, it responds to her emotions and her Starborn light. She didn't choose to carry it, but she's the only one who can use it. The Horn's power is not just dimensional — it resonates with the Gates, with secondlight, with the fundamental architecture of how the Asteri control Midgard. To use it is to challenge the entire system.
The Horn no longer exists as a separate object — it was broken, its power scattered, and eventually reconstituted within Bryce's body as part of her Starborn power. When active, the Horn's mark on her back blazes with white light and the air around her vibrates with a resonant, bone-deep tone. Before it was broken, it was an actual horn — curved, ancient, carved with symbols in a language predating the Fae.
Also known as: The Horn, Luna's Horn