The Chaos Emeralds have been at the centre of many plots by Doctor Eggman. The emeralds have been gathered multiple times and their powers harnessed, having known to have been used to power up the water god Chaos, to power the Eclipse Cannon and numerous other super-weapons usually of Eggman's making. In the majority if these instances Sonic the Hedgehog and others have foiled these plans by harnessing the emeralds power themselves and becoming their Super forms. The emeralds have sometimes been the sought after by other major threats, such as the Black Arms. (VG: StHs)