Fanlin'Deskor (Amber Skies over Wondrous Rock in the Draenei tongue) is the name given to a world by Velen, who witnessed its fall in a vision that he later shared with Anduin Wrynn. The world's real name is unknown as the Burning Legion invaded it and left nothing behind and, according to Velen, "its inhabitants did not speak in ways we understand".
Fanlin'Deskor had four moons, an amber atmosphere, and rock formations made from the blue-tinted ground twisting in a thousand different ways. It was inhabited by a variety of strange creatures, including a group called the Light-Bearers. Upon viewing the world, Anduin couldn't tell if the rock formations were natural or carved by the alien lifeforms. The Light was present on the world, as strong as anywhere on Azeroth.
At some point the Burning Legion invaded the world, ravaging the landscape with armies of demons before a gigantic eredar arrived through a portal and drew symbols of dread power in the dust with his finger. Similar to Archimonde's destruction of Dalaran, this created an explosion of energies that ripped the world's surface apart. After the Legion pulled back, the sky was so clouded that the moons could no longer be seen, and the rock formations had been blasted to dust. Nothing living remained.
During the Cataclysm, Velen showed a vision of the planet's destruction to Anduin in order to illustrate what was at stake in the Burning Crusade. Velen stated that he did not know the world's name and that "Fanlin'Deskor" was simply what he called it. He added that since he doubted the Legion recorded its victims, he and Anduin were likely the only ones in the universe who knew that the planet had existed at all. This was later contradicted: the broker Ta'lora not only knows of Fanlin'Deskor and its inhabitants but also refers to it by the same name as Velen.