Adventure Comics Vol 1 #343

After a series of instances of breaking taboos, and the admission of recent misfortunes from fellow members; Lightning Lord, Bouncing Boy and Star Boy, the Legion believe they might be jinxed. This belief is further amplified when Shrinking Violet and Invisible Kid's powers begin to malfunction.

Saturn Girl decides to investigate this bout of bad luck, believing it's caused by outside forces. Her investigations lead her to the planet Thraun, a place who's people experience nothing but good luck. When her ship is destroyed in space, the Legion go to the planet thinking she too has been struck down by bad luck.

On Thraun, they meet the Luck Lords, and learn that they have Saturn Girl hostage. With the help of the Legion of Super-Pets, they are able to defeat the Luck Lords and turn them over to the Science Police. It is revealed that the Lords were really evil scientists who were using technology (and hypnotism) to strike the Legion down.