Evacuation: Mars
The atmosphere is a dense acrid fug that crackles with electric blue haywire and billows huge luminous green clouds of corrosive acid rain. Only the Skitarii can remain unharmed in the toxic landscape for any period of time and only the cracked and leaking hulks of the remaining buildings offer any kind of protection to the warring armies of 40k. Vehicles and machinery of all kinds have long since lost their power and can be seen as decaying shells littered around the planet, though the Skitarii are able to make their biomachinery function.
The Skitarii are on their way to remove the last few warring factions from their city and the remaining units battle over the last operative teleportation pod that has a single charge left. Whoever controls this pod at the end of the battle will be able to evacuate the city to the waiting crafts in orbit around the Red Planet and escape the indigenous warriors whose arrival is all too imminent.