Trial by Terror - S2.E7

Thundarr's friend Thorac is accused of stealing a village's fuel and is about to receive a death sentence (by being boiled alive over a geyser) when the barbarian rescues him. Thorac is granted a reprieve when Thundarr and the group investigate the crime, eventually learning the town's sheriff Korb is in league with the evil wizard Artemus. Artemus had stolen the fuel to power his Death Ship and gain the approval of the Council of Wizards.