The Fireballs of Plun-Darr - S1.E16

The Mutants, once again searching for a way to destroy the Thundercats, recover some more items from their spaceship. They take their ship's engine and convert it into a giant fireball-shooting machine. The mutants terrorize Third Earth with their fireballs, until the Thundercats go to castle Plunn-Darr and destroy their dangerous new weapon.