The Mirror Looniverse is a world where the LNH are evil conquerors who overran their world, ruling it via ruthless strength, torture, and the might of the Kirbian Police. Most members of this world's LNH are fairly similar to their Looniverse-A counterparts physically and in "heroic" identity, though many, such as Blaster Master, Baron Occultism, and the Ultimate Emperor, have slightly different titles and abilities.
When Particle Man participated in an experiment intended to explore the borders of quantum physics, he ended up shot across the Omnilooniverse, and eventually landed here. He managed to flatter his way past several evil Legionnaires, but was stopped cold by Blaster Master – who had killed his counterpart, and aimed to destroy him too!
During the world-hopping storylines in Cute Anna, Crypt Looter, Deja Dude and his allies traveled through this universe. In Flame Wars VI, it was one of the worlds merged by Excess to fight the Anti-Moderator, with the Ultimate Emperor amalgamated with the other counterparts of Ultimate Ninja.