Dark Spark

The Dark Spark is an ancient dark relic that was said to be the equal but opposite force to the Matrix of Leadership. Whilst the Matrix granted wisdom, its antithesis allowed its wielder to bend the fabric of the universe and its inhabitants to his will. Possessing some similarity to Dark Energon, it can reanimate the dead, granting its owner command over them. Apparently, it can also travel between dimensions. Originally, the Dark Spark was wielded by Galvatron against the Autobots in the Generation One dimension before ultimately being cast into space.

Eventually the Dark Spark arrived in the Robot Defenders dimension, where it was discovered by Decepticon forces. Megatron saw an opportunity to even the odds against the Autobots and took possession of the relic. This allowed Megatron to match Optimus Prime evenly and in a way seemed to confirm Megatron's role as Leader of the Decepticons further.