Prometheus
From Warhammer 40k - Lexicanum
Prometheus
Prometheus is Nocturne's moon and the Fortress-monastery of the Salamanders. The monastery is the only construction built there and has a great dock were the chapters' Strike Cruisers and Battle Barges can be restored. Being an over-sized moon, it causes massive stress in the planet's tectonic plates.
An event, which is known as the Time of Trials, occurs every Nocturne year (15 Terran years) . During this time, the planets' thousands of active volcanoes erupt and the seas rise up in vast waves.1