Rathrea

The rathrea were a type of undead dragon from Laerakond. Dragonborn called them ghost dragons.

Creation
Rathrea were created when dragons who failed to awaken after having consumed arambar. Those dragons eventually transformed into wraith-like, incorporeal glowing white spirits who had the ability to divine the future. This ability was limited to certain areas of information and time-spans.

The rathrea didn't live for much time, fading away in a few weeks. According to Gauwervyndhal, those rathrea "ascended" after they disappeared.

History
The Empress Dragon Gauwervyndhal prized the rathrea for their ability, as it allowed her to outmaneuver her enemies. Gauwervyndhal forced many of her dragon servants, even her own children, to consume arambar in order to procure more rathrea.