Arvala-7 is a hot desert world of wind-worn mountains, baking deserts, conversely, vast fields of dried mud with crevasses hundreds of metres deep, legacy of the torrential rains that happen for a few short weeks every decade or so. These rains originate from the small sea in Arvala-7s northern hemisphere, the Sea of Kurnak. The level and salinity of this sea vary significantly, with the are expanding to almost twice its normal size after the rains, then slowly shrinking to its regular confines over a 10 year period. The water that evaporates from this sea over the preceding decade is dumped on the planet in a wild deluge in which more than two metres can fall each day over a period of three weeks. During this time, the deserts are transformed into vast shallow lakes full of turbulent, swirling waters. The local wildlife is sensitive to this cycle and tends to migrate to the mountainous and rocky areas to find shelter in caves or under outcroppings. Despite this, these deluges will normally cull at least twenty percent of animal life on Arvala-7.

Once the deluge is over, the shallow seas empty rapidly, flowing quickly over the land and carving our deep channels in the mud, which when dry, form a key part of Arvala-7s landscape. With average temperatures significantly higher than an average humanoid can withstand for more than a few hours, the planet swiftly returns to its dry and desiccated shape, with only shallow pools and oases surviving for any length of time. These areas are hotly contested by the world’s wildlife, including the ubiquitous mudhorn, the gregarious ronto and ferocious sand panther as well as serving as water reserves for many a small town or settlement.