Eric was a drone used by Dollar Intergalactic in terraforming Isen VI.
He and Clarence were sent to retrieve an unidentified spacecraft and detain its crew when the Doctor's TARDIS was noticed by Terra-Sphere Control. However, the Twelfth Doctor reprogrammed both drones to rock to some tunes stored in their memory banks.
Later, Eric was reprogrammed by Rann-Korr and attacked Clara Oswald. Their fencing duel ended with Clara pushing him into molten lava. (COMIC: Terrorformer)