Legion of the Lost
Vildar was a planet attacked by the Daleks during the Last Great Time War. The War Doctor witnessed the death of Collis on the planet.
The Doctor had visited Vildar before the attack, in an earlier incarnation. He remembered that the “skies were made of dreams”. Collis was told that the Daleks specifically targeted the Vildarans for erasure by Annihilator because of their artistic and intellectual leanings. (Legion of the Lost)