Superboy Vol. 1 (1949-1976) / Superboy and the Legion of Super-Heroes (1976-1979) #198

Plot

At a carnival in his own time period, Superboy faces the Fatal Five. A Legion team trails the Fatal Five to Superboy's time, while, due to a time-distortion machine placed in Superboy's time by the Fatal Five, the rest of the Legion and their headquarters fade from existence in the future. The Legion team in Superboy's time disables the time-distorting machine, and so in the future Legion headquarters rematerializes, imprisoning Mano and Tharok.