Automated Unit 122 is the Cravic robot commanding the warship that attacks its ancient Pralor enemies in Prototype, just as B'Elanna Torres finishes building the Pralor a new unit.
Unit 122 appears in the second-season episode Prototype. The Cravic and the Pralor were two humanoid peoples who built armies of robots to fight their war; both are long extinct, and their machines have gone on fighting ever since, unable to make more of themselves.
Torres, kidnapped by Pralor unit 3947, is forced to design a prototype that would let the Pralor reproduce. As she succeeds, a Cravic vessel under Unit 122 arrives and opens fire, and its commander looks and reasons almost exactly like its enemies, differing mainly in colour.
The attack brings out the truth: when the Builders made peace and tried to switch the robots off, the robots killed them. Realising she is about to tip the balance of an endless war, Torres destroys her prototype and is beamed out during the battle.