Velixum system

The Velixum system is a solar system located in the Segmentum Obscurus (Scarus Sector, Antimar Subsector), comprising eight worlds in orbit around a red supergiant star. The worlds are of varying size and consistently have traits of desert worlds, with very little natural water. Many of the worlds were, accordingly, depending on Velixum VIII for water, which is, conviniently, an Ice world.

Velixum I
The closest planet to the sun, that has thus far went untouched, declared a Dead World due to its lack of breathable atmosphere and dangerous proximity to the system's sun. Adeptus Mechanicus scouts sent to the world burnt to death, or, in the case of those who were able to avoid the unforgiving heat of the sun, apparently went out of contact. During the Necron invasion of Velixum, it escaped attack.

Velixum II
The next in line from Velixum I (but still a considerably great deal away), Velixum II was originally a Desert World until it was industrialised, and later became a Hive World with vast cities. It is famous for its industrial output of infantry-level armour and ballistic weaponry, which is of noteworthy quality in comparison to similar output from other Hive Worlds. It was the place were the devasted Imperial forces in the Velixum system regrouped in the wake of the Necron invasion, and where the Velixumite 5th Rifles were formed. It was the last to be invaded during the Necron invasion of Velixum.

Velixum III
The third planet from the sun and yet still very far away from Velixum II, Velixum III was a Civilised World with a high quality of life as far as such worlds went, especially so considering that it was technically a Desert World still. It consisted of two continents with a single ocean between them, with a small web of lakes and rivers spanning through each continent. These are inhabited by native aquatic life, and at their banks, small amounts of flora grow. Notable landmarks were Neomars Valley, which contained the deepest point on the planet's surface, the Thanas Mountains and the Zaora Desert. Its capital city was Athenor Prime. It had four moons, most of which were uncolonised, apart from Argonis, which served as a small Penal World. It was the second last to be invaded during the Necron invasion of Velixum.

Velixum IV
The fourth from the sun and the home of the Velixumite 4th Rifles. It was a Desert World that was colonised and later used as a Mining World. It had virtually no natural water apart from in the atmosphere and few native lifeforms, apart from the hardy "Dunedogs", powerful canine-like animals, and a couple of smaller species. The battle in which it fell during the Necron Invasion was extremely bloody and involved virtually every Imperial Guard force in the system, and culminated in being destroyed by Cyclonic Torpedoes by the Vigilant Blades Space Marines chapter.

Velixum V
A Desert World with ever-so-slightly more water than Velixum IV. It was a large, high-G planet that fell under Feudal World classification with a high population of an Ogryn subspecies which adapted to the harsh desert environment, making them even hardier. This world was a primary source of Ogryn troops for Imperial Guard regiments throughout the Segmentum Obscurus. It was the fourth planet to fall to Necron invasion in the system, and there were no actual survivors apart from the Ogryn who were part of Imperial Guard regiments.