Transformers Energon Season 1 Episode 52

Optimus Prime's efforts to drain Unicron's power out of Galvatron have rendered him lifeless. In this moment of opportunity, Galvatron decides to head straight for the heart of Unicron, the very source of the omnicidal terror, in hopes he can destroy it as revenge for using him as a puppet. Kicker, already standing before Unicron's heart, contemplates destroying it, but is stopped by the voice of Primus. Unicron is actually a force that can be used to create life, not just take it. However, even with the help of Omega Supreme, Galvatron seizes the heart and grows to planetary proportions, fully overtaken by Unicron's evil. Primus anticipates Galvatron's arrival and decides to merge his essence with the Super Energon, sending a thermo-nuclear nova to destroy him, but causing him to go dormant.

In this darkest hour, the only hope left for the universe is Optimus Prime, but what can the Autobots do to bring their leader back? The answer lies in their powers to combine.