The Fist of Nod is Nod's answer to GDI's Mobile War Factory, introduced in Firestorm.
When deployed, things were different. The Fist of Nod could produce any Nod Vehicle that required a tech center or lower to produce, including Stealth tanks and Subterranean APCs. This reflects its namesake: the mobile factory produces Nod's weapons closer to the enemy, like throwing a fist at them.
Therefore, it could not produce another Fist of Nod. Once deployed, it could not be repaired by conventional ways (with the exception of theMobile Repair Vehicle) - but it could be captured by an engineer. Also, unlike the MCV, a deployed Fist of Nod could redeploy and move somewhere else.
The name is a play off the Hand of Nod, although the Fist constructs vehicles rather than infantry. Also,
since Vehicles are relatively stronger then Infantry, it could relate to the Fist (a punch) being stronger then the hand (a slap).
A Fist of Nod, which was equipped with a massive amount of raw materials, almost single handedly constructed the army which destroyed CABAL's harvesting operations during the Firestorm Crisis. However, while it was most definitely used in the second Nod civil war following the Second Tiberium War, all units were decommissioned or had been destroyed by the time Nod had become a reunited force.
The Fist cannot be repaired like a conventional building even when deployed. It requires a mobile repair vehicle. When deployed it may be captured by an engineer. Build options are identical to the regular war factory and respects the tech tree.