Materioptikon

The Materioptikon was a weapon designed by the villainous Doctor Destiny, who wielded it against the Justice League, creating illusions of a false world ruled by a fascist League.

Its power was so great, it was able to start the forceful integration of Destiny's world into the real timeline. While defeated and separated from the Materioptikon, he was able to simply make another one out of his own dreams.

When Destiny then proved he could continue doing this for as long as he could dream of the Materioptikon, the League then resorted to changing Destiny's mind so he could not dream at all, causing his transformation into the monster he later became.

Appearances
Earth-One Appearance:
 * Justice League of America, Vol. 1 #19 (May, 1963)
 * Justice League of America Vol. 1 #61 (March 1968)

Earth-1A Appearance:
 * SuperFriends Comic Book: Limited Collectors' Edition #C-41 (December 1975 / January 1976)