Challenge of the GoBots: Battle of the Rock Lords, also known as simply GoBots: Battle of the Rock Lords, Challenge of the GoBots: Rock Lords or GoBots: Rock Lords, is a 1986 American animated film based on the Gobots line of toys. It was produced by Hanna-Barbera Productions (also responsible for the Challenge of the GoBots television series) and released to theaters in 1986 by Clubhouse Pictures, the last film the company released. It featured the first appearance of the Rock Lords, who were given their own toyline after the film.
The Guardian Gobots are continuing their work on rebuilding their home planet of Gobotron when a mysterious ship crashes on the planet. Leader-1, Turbo, and Scooter investigate, and find it to be occupied by a pair of transforming robotic rocks with protosaur essences – Solitaire and her valet Nuggit. They have come seeking the Guardians’ help to save their planet, Quartex, from the evil Rock Lord Magmar, who is killing the other Rock Lords in order to take their power sceptres. He places these in a machine designed to channel all their power into his own sceptre.
The Guardians agree to help, but the conversation is spied upon by the Renegade Fitor. Gobotron is soon attacked by the Renegade fleet, and Cy-Kill and a team of Renegades capture Solitaire, Small Foot and the GoBots’ human allies Nick and A.J. With Nuggit as their guide, Leader-1, Turbo, Scooter, and Matt set off on a rescue mission.
On Quartex, after relieving a vanquished Rock Lord of his sceptre, Magmar now only requires three more to complete his own. One is held by the Lord of Fossils, another by Solitaire, and the last by Boulder and his forces; the only opposition left. His troops vote to attack Boulder and be done with him, but Boulder learns of the upcoming attack, and is able to launch an effective counter defence that sees Magmar on the verge of defeat.
Meanwhile, Cy-Kill attempts to get information out of Solitaire, and despite her best efforts manages to link up with Magmar and strike an alliance, turning the battle against Boulder. The good Rock Lords flee, and after their defeat at the hands of the Renegades are initially very skeptical about the Guardians’ intentions when they land on Quartex. However, Nuggit is able to convince Boulder and the rest of the Guardians true intentions and the two sides form an alliance.
The Renegades and Magmar soon attack in Thruster, and Leader-1 and Turbo engage in aerial combat, but receive damage that impairs their ability to fly or convert to vehicle mode. Thruster eventually withdraws on the belief that the Guardians and their allies have been wiped-out, but they survive and proceed towards the kingdom of Fossils before it is attacked. Cy-Kill and Magmar, however, strike first and seize the Fossil Lord’s sceptre, leaving our heroes at a loss on what to do next.
Meanwhile on Rogue Star, after Nick and A.J. escape from their cell, they free Small Foot, and the three carry out various acts of sabotage before escaping in a Renegade Spacehawk fighter. They land on Quartex and hook up with Leader-1 and the rest. Cannibalizing the fighter for all its parts, Scooter is able to construct energy projectile weapons for Boulder and his troops, and fully repairs Leader-1 and Turbo.
Now ready and with the element of surprise, the allies march on Stonehead, Magmar’s fort. Meanwhile, Cy-Kill finally hands Solitaire’s Sceptre to Magmar to fully power his own (Boulder’s sceptre, which they believed lost and was described as necessary to Magmar’s goals, is all but forgotten). Once the sceptre is powered, Cy-Kill and his Renegades make their move to seize it for themselves.
Solitaire, who is present to be executed, escapes in the shoot out, and rejoins Boulder and the rest as they finally crash the party. The Renegades flee with the stolen sceptre, but the Guardians pursue. Discovering that Thruster has been wrecked by the Guardians prior to their attack, Cy-Kill attempts to use Magmar’s sceptre against them. But the energy discharges are too much and he is unable to control or even release his hold.
A well placed shot by Leader-1 separates the two, and the Renegades finally retreat while the sceptre’s power disperses. Magmar and his minions remain at large, but are no longer unopposed. With their mission complete, the Guardians bid farewell to the Rock Lords and return to Gobotron.