Mobile Artillery are mounted on several wheels that grant them a high movement rate, while also holding them upright and stable. They are armed with a Gatling-style cannon, a missile launcher, and a single, high-powered cannon. The operating seat is located between the side weapons and under the main cannon.
Dora is first shown having crashed into a house in the Residential District, surrounded by a crowd. When Shulk goes to the Military District, he sees Colonel Vangarre yelling at the Defence Force soldiers who crashed it by going too fast on the way to the Military District. The ether conduction cable was damaged in the crash, causing all the ether fuel to leak out of the Cylinder. Reyn is sent off to fetch a new Cylinder to power the Mobile Artillery while repairs are performed on it; Shulk is dragged along with him and Fiora meets them outside Tephra Cave, which leads to the Cylinder Hangar. When the Mechon raid begins, the group is unable to retrieve the Monado due to a blockage; their initial idea is to use the Mobile Artillery to blast the rubble out of the way. However, they are blocked by a group of Mechon and a falling rock. While Fiora attends to the Mobile Artillery, Shulk and Reyn protect her from the Mechon. They are separated by the rock, forcing Shulk and Reyn (and later Dunban) to take the long way around to meet Fiora.
As they arrive they are blocked off by Metal Face. After a short battle, in an intense scene, Fiora pilots Dora, unloading the entire Missile Rounds supply at Metal Face. When this fails she charges Metal Face with Dora. Upon hitting its face, she blasts it with the cannon. Unfortunately, this simply angers Metal Face, who proceeds to throw the Mobile Artillery around like a toy and stab Fiora.
After this, Dora is not seen again.
A machine built on the frame of the Mobile Artillery can be seen during the battle with Xord in the lowest reaches of the Ether Mines. It lacks the main cannon, and the side weaponry has been replaced with two grabbers. Otharon uses it to push Xord into the Ether River.
The prologue shows Mobile Artillery being used in the Battle of Sword Valley. Broken units from the battle can be seen along Sword Valley one year later. During the Second Battle of Sword Valley, there are several Homs soldiers piloting Mobile Artillery.
- It is never made clear how Fiora knows how to use or refuel the Artillery, despite her not being a member of the Defense Force. However, it is said to be easy to control. She may also have learned from her older brother Dunban.
- The Mobile Artillery uses a specific type of Ether Cylinder for fuel, because it requires very pure, high quality ether.
- The name "Dora", as well as the Mobile Artillery unit being in the possession of Vangarre, is a reference to earlier Xeno games. In Xenogears, Dora was a Gear piloted by Vanderkaum. A mech called "Proto Dora" appeared in Episode I of Xenosaga; in Xenosaga I & II it was instead piloted by Vanderkam during Episode II, in order to reference Xenogears. In Xenoblade Chronicles, Vangarre is a counterpart to Vanderkaum and Vanderkam.
- The French version of Xenoblade: The Secret File does not mention Dora's name.