Hȳf

Hȳf was a planet inhabited by numerous Racnoss.

Geography
Hȳf's landscape was barren, and filled with vast black, white and grey-coloured rocky wastelands. Despite this, the planet was an ideal home for a large population of Racnoss, who lived in warrens under the planet's surface.

Since its weather system was formed, Hȳf was in a constant storm. However, when the Ninth Cyber Legion's troop carriers descended onto Hȳf's surface, the planet's atmosphere was compressed, transforming the clouds into a mist over the wastes. This invasion marked Hȳf's first blue sky in a hundred million years. (PROSE: Ghost in the Machine)

History
At some point, Hȳf was inhabited by a large population of Racnoss, who lived in warrens underneath the planet's surface. When the Ninth Cyber Legion invaded the planet, numerous troop carriers landed on Hȳf's surface, and a vast army of Cybermen, including 9.9P-VIV and nine other Primus Cybermen, engaged the Racnoss in a brutal battle. The Cyber-Controller of the Ninth Cyber Legion had chosen to use Hȳf as a testing ground for a new type of Cyber wrist blaster to see if it would be useful as a standard weapon in all future Cybermen.

The battle between the Racnoss and the Cybermen resulted in the deaths of numerous Cybermen and even more Racnoss. During the battle, 9.9P-VIV appeared to hallucinate, for the first of many times, the appearance of a human girl amongst the Racnoss, but was unable to register any information about her other than her appearance.

The battle ultimately ended with the Cybermen being ordered to return to their troop carriers, although the Cyber-Controller never stated whether or not the Cybermen had successfully defeated the Racnoss of Hȳf. (PROSE: Ghost in the Machine)