>>39754281X-Antibody in lore is the result of Yggdrasil (the god of the digital world) thinking that the servers that Digimon is on running out of space. To combat this, he decides to take 2% of the species and move them to a new world and eradicate the rest. He creates a virus that starts wiping everyone out, however some have the x-antibody form in their Digi-Core. This is like the cure for the virus and they can survive. However, this makes Yggdrasil mad and he sends his Royal Knights out to murder these guys....so stuff happens. Watch X-Evolution, a version of it is on YouTube currently.