From the Vault: Adventure Comics 300

      The story opens at a meeting of the Legion of super-heroes with few members around to do missions. Cosmic Boy mentions that the meeting is being filmed and soon to be broadcast on many worlds as a warning to crooks when the camera. Sun Boy accuses him of attacking it when his own powers start acting up. Lighting Boy power also starts acting up as well. Saturn Girl goes to use her powers and causes pain to the other three as she too loses control. She runs and pulls a lever to summer Superboy.



     In the past Clark Kent is at Smallville reformatory where a young Lex Luthor has been released. Clark says he hopes Lex will go strait and forget his hate fro Superboy. Later on Clark is in his room and is thinking of putting him in the Phantom Zone. This makes him think of Mon-EL who he had to put in the Phantom Zone. Just as Clark finishes thinking of this the Legion of Super-heroes ask for him.
    Clark get to the future and sees that the Legion is destroying its Clubhouse. He repairs the Clubhouse and then asks why this is happening. Suddenly Sun Boy powers start acting up again and he uses his anti-gravity belt to get away. He ends up melting some of the Arctic. When he returns Superboy spots more trouble.
    A craft from the World-Wide Police comes down and says they have an hour to regain control of their powers or they will be expired from Earth.
    Superboy tries to figure out whats wrong when a mask men by the name of Urthlo shows up and says he has caused the powers to not work right. The heroes try to act but he shuts off their powers and use Green Kryptorite vision on Superboy. The Legion is then forced to flee.
   Sometime later Saturn Girl comes up with a plan. Thy travel to a spot and Saturn Girl asks Superboy to dig a hole to get a buried Legion item. The item Superboy gets is a phantom Zone projector and Saturn Girl asks Superboy to get Mon-EL out of the Zone.
   Superboy gets him out and he appears in pain. Suddenly Urthlo appears and Saturn Girl asks him to drink something. Suddenly he has his powers back and is able to defeat Urthlo even with the lead mask and we find out that it is a robot as it is damaged/destroyed. Superbo then asks what is in the bottle. She lets it be known it's a antidote for lead poisoning.
  Saturn Girl had diagnosed the problem by talking to Mon-EL in the phantom zone. Sadly it's effects do not last for very long. Superboy then removes the mask on the robot and it has the face of a adult Lex Luthor. The Legion no longer has to go into exile and Mon-EL becomes a member of the Legion. However the serum goes off and Superboy puts Mon-El back in the Phantom Zone. Superboy then returns to his own time era.