Tales of the Legion of Super-Heroes in "Lex Luthor Meets the Legion of Super-Heroes" *Khann, a world inhabited only by criminals, is run by strange beings known as the Brain-Lords. Matter-Eater Lad and Triplicate Girl journey there hoping to capture the chief lord, Atro, and take him to Earth for punishment. During their attempt, Atro and the other Brain-Lords alert the populace, who try to prevent their escape. A strange craft suddenly appears to save them, and all return to the Super-Hero Clubhouse on Earth. There their mysterious rescuer reveals himself to be a young Lex Luthor, who has apparantly come visiting from a 20th century before the tragic accident that turned him criminal.
The Legion vows not to tell Lex of his fate, and attempts to entertain him instead. Mon-El and Light Lass inadvertently reveal the secret, however, and Lex is informed of his destiny. Since they cannot alter history, Lex leaves them, only to secretly double back and snatch away the wig which had disguised his baldness. His previous attitude was a charade, and his real goal is to integrate himself with the heroes, and then kill them.
Supposedly reconstructing a dissolver-ray he saw on display in the Clubhouse, Lex summons various Legionnaires to different locations, and then disintegrates them with the ray. Actually, he has built a disguised Phantom Zone projector instead. From inside the Zone, Mon-El instructs his fellow members to use mental commands to force Lex to release them. This occurs on television before a galaxy-wide audience, and the heroes destroy the projector. They then allow Lex to return to his own era in humiliation, a laughingstock on hundreds of worlds. *Source: The Official Legion of Super-Heroes Index #3.
An untitled Professor Eureka strip.
The Legion of Super-Heroes Constitution, Part 1
Superboy in "The Day Superboy was a Coward"
Reprinted from Superboy (Vol 1) #72.