Doomstone

The Doomstone is a powerful crystal formed within the chest compartment of Nemesis Prime as he (it?) travelled across the universe destroying planets, and was eventually transferred to Ravenus.

It contains the collected and condensed negative psychic energies of Nemesis Prime's victims; their pain, agony, suffering and despair. The minions of Unicron put the Doomstone into Ravenus and used his enhanced Powerlinx command to kidnap the "free" Mini-Cons Twirl_(UT) and Servo_(UT), planning to se the link formed with the Powerlinx to release the Doomstone's energies into the Linkage, destroying the souls and minds of all Mini-Cons and returning them to the mindless engines of destruction they were created to be. And should the crystal be improperly handled, its energies would wipe out all life on whatever planet it was on - in this case, Earth.

The minions of Unicron were just a hair too late, though. Thanks to the intervention of Redline and Kingbolt_(UT), Ravenus was contained, and the newly-enhanced Mini-Cons were able to extract the Doomstone. Redline sealed it inside his extra-dimenisonal storage space to protect it from harm until they could figure out how to properly deal with it.