He heard the voice of Xoanon at his shrine, a voice that, unknown to him, came through a communicator — another residual piece of technology. Neeva told Andor that it was Xoanon's will that they should attack the Tesh, another tribe on the planet. When Leela criticised this plan, and went on to blaspheme against the tribe's god, Neeva persuaded Andor to banish her. After this had been carried out, he sent two men after Leela to kill her.
Based on the sculpted face on a nearby mountain, the Fourth Doctor was believed to be the "Evil One" — the being who had Xoanon captured. As the creed of the tribe instructed, Neeva ordered the Doctor's execution, but he escaped before it could be carried out. The shaman lied to the tribe, telling them he was dead.
After the attack on the Tesh, and the discovery that the Doctor was still alive, some members of the tribe openly questioned Neeva's credibility. They agreed to test the Doctor's status in the traditional manner — he had to stand over the Horda pit and shoot a rope with a crossbow before he fell. He succeeded.
Neeva continued to communicate with Xoanon, but gradually realised he was not talking to a god. Viewing this as a betrayal, Neeva travelled to the ship in which the original humans arrived with the intention of killing Xoanon — a supercomputer. He attacked his former deity with a Tesh weapon, releasing those who were being mind-controlled and allowing the Doctor to wipe his own personality from the computer, making it whole and sane again. Neeva died in the process. (TV: The Face of Evil)