Dark Rings

The Dark Rings were created by the  Digimon Emperor, and are overly reminiscent of  Devimon 's  Black Gears. The rings are capable of independent flight, and are outfitted with cameras, which transmit images back to the Emperor's throne room in his base. When a Dark Ring attaches itself to a  Digimon, it takes control of their mind, placing them under the Emperor's complete control. The Emperor's shades are linked to the rings, and send orders directly from his mind to the minds of the Digimon, via the rings. Dark Rings are only powerful enough to control Digimon at the  Champion  level or below - the Emperor discovered this when he attempted to have  Greymon  become MetalGreymon  while under the power of a Dark Ring. Greymon fought the power of the ring, and the  Digivolving  process, which corrupted and once again transformed him into  SkullGreymon, who was unaffected by the ring. To capture  Ultimate  Digimon, the Emperor created the  Dark Spirals. Dark Rings first appear in "Enter Flamedramon."