Superboy (1949-1979 1st Series DC) #203
Cover art by Nick Cardy. Massacre by Remote Control, script by Cary Bates, art by Mike Grell; After the Legionnaires run a practice drill on protecting their headquarters, Invisible Kid collapses; He reveals that when he turns invisible he can see an invisible world and one of its inhabitants, Myla; Later, Dream Girl dreams that Validus is coming to attack the Legion; Saturn Girl confirms that the components of Tharok's brain being held by the Legion are summoning Validus; Validus attacks Legion headquarters and kills Invisible Kid just as he destroys the components of Tharok's brain controlling Validus.
