Also known as The Great Amplifier, Megarek is a massive boulder of an Overstone, capable of amplifying and even reversing the powers of other Overstones.

Long thought to be a myth, Megarek is enshrined within the ruins of what appears to be some sort of temple, complete with statues of Minzki, Lord of the Underworld.

As Megarek has only recently been introduced, its history and exact extent of its powers are unknown. However, in the story, a user was apparently able to use it to turn humans into Toadmen on a global scale.