Plasma Energy Chamber

The Plasma Energy Chamber is a reservoir of plasma energy.

The Transformers cartoon
According to Optimus Prime, the Plasma Energy Chamber was the foundry where the original Autobots' bodies were forged, millions of years ago. Since that time, every Autobot leader's duties included guarding the key to the Chamber. The Chamber was located on Cybertron, twelve levels below Generator C.

Unfortunately, the key was stolen during an all-out Decepticon assault on Autobot City. The Autobots managed to get back the key on Nebulos but failed to keep it when Scorponok got into the fray. The Autobots and Decepticons returned to Cybertron and continued to battle over the key but Galvatron used it to open the chamber and unleash the energies on Earth's Sun. Spike found a way to reabsorb the plasma energy back into Vector Sigma and restore Cybertron to its Golden Age.

3H comics
The Plasma Energy Chamber was an attempt by the Quintessons at controlling Primus, but it failed and created the Trans-Organics.

Beast Machines cartoon
Optimus Primal saw a vision that the Plasma Energy Chamber could help them against Megatron and his Vehicon forces. During a desperate hour, when Megatron had defeated all the Maximals with the Key to Vector Sigma, Optimus opened the Plasma Energy Chamber. The energy of the Key clashed with the energy from the Plasma Energy Chamber, threatening to tear Cybertron apart, but Optimus was able to channel the energies into the Matrix.

Exodus
Megatron tried to use the Plasma Energy Chamber to spread his Dark Energon influence across Cybertron. Despite Omega Supreme's efforts, Megatron was successful and continued for the Core of Cybertron.