Superboy Vol 1 #208

In Superboy Vol. 1 #208, Superboy, Mon-El, and Ultra-Boy are incapacitated by their own parents, who are revealed to be controlled by the Legion of Super-Villains via hypnotic beams. The issue also features an introductory page for the Legion of Substitute Heroes, a splinter group of rejected Legion applicants who have since proven themselves.  
Plot:
Hypnotic Control: The primary story revolves around the Legion of Super-Villains' scheme to strike down Superboy, Mon-El, and Ultra-Boy using hypnotic beams that manipulate their parents into attacking them. 
Introduction to the Legion of Substitute Heroes: The issue also includes a special feature introducing the Legion of Substitute Heroes, a team of heroes with less conventional powers who were initially rejected by the main Legion.