One day, a Dr. Von Kelm invented a machine that made mirrors in to portals to another world. From that world escaped monsters!

The tried to conquer Earth, but were sent back to their world by Kid Eternity and his companions!

Nothing else is known of the monsters. Mr. Keeper theorized that their world had become a terrible place to live, and they wanted Earth to be their new home.

Powers

They were/are brutishly strong, and nothing that pierces trough them can harm them! But ordinary punches and kicks can. They also have telepathic powers. This gives them the ability to learn any language instantly, anticipate their opponents every move and probe other knowlege from minds. They cannot concentrate on multiple persons at once.