The Plasma Energy Chamber

Beneath Cybertron's crust, above Vector Sigma, sits the Plasma Energy Chamber: a sealed vault of raw plasma energy that predates the war and is dangerous enough that it has been kept shut for as long as anyone can remember. It is the planet's furnace, the reason a metal world can be alive at all, and the G1 cartoon saves it for its final story.

In The Rebirth, Part 1 Galvatron invades Cybertron, builds a massive planetary engine and pushes the entire planet back into Earth orbit, then opens the chamber. The plan is annihilation on a scale even Galvatron rarely attempts: the released energy is meant to drive Earth's sun supernova, consuming Earth, Cybertron and the Decepticons' problems in one stroke. The escaping plasma is loose for most of the three-part finale, and the story becomes a race to contain something that cannot be fought.

The resolution reframes everything. In Part 2 Alpha Trion, speaking through Vector Sigma, reveals that the entire crisis was engineered by Vector Sigma itself to force a new Golden Age. In Part 3 Spike Witwicky and the Autobots' Nebulan allies reverse the planetary engine, which drains the excess solar energy and channels it into Vector Sigma, which uses it to re-energise Cybertron completely. The planet's gold colour returns. The chamber that was going to kill a solar system instead ends the war's energy crisis, which is the tidiest thing the G1 cartoon ever did.

• The Rebirth was originally planned as a five-part story and was compressed to three, which is why the Plasma Energy Chamber plot moves at such speed.
• The chamber reappears as a central plot device in Beast Machines, pitted directly against the Key to Vector Sigma.
• The Rebirth is not considered canon in Japan, where The Headmasters series replaces it, so the Japanese Cybertron never gets its Golden Age this way.
• Opening the chamber is the only time in G1 that a Decepticon plan would have destroyed Cybertron along with everything else, and Galvatron does it knowingly.