ThunderCats S01E54 - The Transfer

A spaceship approaches Third Earth and it sets off all the alarms of the Thundercats, Mutants and even Mumm-Ra. It contains enough radioactive material to put an end to the Thundercats. Jackalmantakes the recovered materials first and Mumm-Ra takes it from him. The Thundercats battle Mumm-Ra on top of the Black Pyramid for the sphere and eventually win, setting the materials to explode safely in space.