 
Alien X is the Codon Stream's DNA sample of a Celestialsapien from The Forge of Creation.
Alien X has shown to be omnipotent, able to warp reality and time/space itself, becoming nearly invincible.
Alien X's reality warping is so powerful, that his mere thoughts can become real.
Because Alien X is Ben's most powerful alien or Ben thinks, as Dwayne states that Alien X is not the most powerful alien in the Codon Stream, but does carry the most risk.