The War Rig is a multi-functional mobile structure used by the Epsilon Army. It is the replacement to the Slave Miner from the vanilla game (though the Slave Miner still exists in the mod as of version 3.3.4, it can only be added through the FinalOmega map editor).
At first glance, this building is not much different from Epsilon's regular Ore Refinery, but the fact is that the War Rig, known as "the Epsilon's Swiss Army Knife", serves more than just providing an ore unloading point. It can provide repair services for the surrounding vehicles, just like the SovietRepair Crane. The building's top is equipped with an Amnesia Ray, same as the Ruiner's, to deprive the attack capability of enemy soldiers who approach it. Moreover, the same active energy emitters as those in the Synthesis Vault are contained inside the Rig, to reinforce any nearby Tank Bunkers.
On top of all that, numerous drills from the War Rig will be launched towards enemy positions and emerge from underground to cause heavy damage when the enemy vehicles are passing by. The drills are also relatively effective against structures, meaning the Rig can be used for direct assault as a last resort.
Probably the most terrifying detail of this construction is, that the War Rig with all its utilities can still be packed into a vehicle state, so that it can be deployed in different ore zones to provide unloading services there. War Rig in its mobile form has the ability to move underground and can smash anything in its way with the drills that are visibly mounted on its front in this mode, rather than hidden underground.
First War Rig is usable in Obsidian Sands, though it is not buildable in this mission.