What is the Dark Legion?

The Dark Legion are the horrendous masses of dead and undead like creatures that were released when humanity became too curious. Humanity, in an effort to explore all aspects of the solar system and to open up new possibilities for colonization, released the great evil (to be called later the Dark Legion) when they looked too deep into Pluto. The Dark Legion would become the greatest nemesis of the Cardinal and the Brotherhood. All living creatures would soon become susceptible to corruption by the evil that the Dark Legion brought. The player's mission, as a Doomtrooper, is to rid the Solar System of this evil.