- You may be looking for the eighth audio set in Big Finish's Gallifrey series.
Gallifrey Eight was one of the Nine Gallifreys created during the War. It contained loomstacks and chronoforges which threw biodata soot into the air, obscuring the sun over the Citadel. Homunculette and the War King visited Gallifrey Eight after the battle at Delphon. (PROSE: The Taking of Planet 5)