In Adventure 343 (April 66) Edmond Hamilton introduces the Luck Lords, and the possibility that all the bad things that have befallen the Legion recently have a supernatural origin. Curt Swan does his usual excellent work on this story, and I particularly like the bizarre tower he created for the Luck Lords.
The Legionnaires discuss the ideas of bad luck on various worlds, in various cultures. Chameleon Boy gets Proty II to turn into a jinx stone, which Durlans consider unlucky. As a joke, the other Legionnaires touch it (as do the Super-Pets), and then bad luck starts to befall them.
Suspicion begins to run rife within the team. Lightning Lad, Star Boy, Bouncing Boy and Duo Damsel all realize they did something “unlucky” before their tragedies struck them.
The Legion head to Thaun, the most superstitious planet in the galaxy, and the home of the legendary Luck Lords.
The resolution is a bit of a let-down, as the Luck Lords turn out to be nothing more than aliens with a long range hypnotic ray, the cause the of the Legion’s recent problems, but not the events from earlier issue. The Super-Pets, who are immune to the ray, are called on to defeat them, which is fun.
The Luck Lords return many years down the road, but in all further stories they truly are supernatural beings. So these ones are just straight out frauds.