History
After the Decepticons broke into the Plasma Energy Chamber, unleashing waves of powerful plasma energy, Chromedome was amongst the group of Autobots flung halfway across the galaxy to Nebulos. After a misunderstanding—namely, the Nebulans threatening to detonate magnetic bombs they had attached to the Autobots after their capture—Chromedome willingly became a Headmaster. He presumably joined the rest of the Autobots in celebration after Scorponok was flung into space and a new Golden Age began on Cybertron. The Rebirth