The X-Antibody (X抗体 X-Koutai) is an antibody that makes Digimon resistant to Program X. During the events of Digimon Chronicle, the X Program was used to delete Digimon overpopulating the Old Digital World, but strong enough Digimon with strong survival instincts resisted the effects of the X Program and were able to survive by altering their Digicores. These Digimon were reborn in a form that incorporates X Program itself into their Digicore and thus created the X-Antibody. However, X-Antibody in Digicore will disappear if it continues to be exposed to the X-Program for an extended period of time, but this can be prevented by absorbing more antibodies. Also, digimon without X-Antibody can also acquire it by stealing it from other Digimon who have it. This makes baby Digimon like Tokomon X (a rare case of baby digimon acquiring the X-Antibody) an easy target to get it. But, digimon that naturally possess the X-Antibody (such as Alphamon, Tobucatmon, or Metalpiranhmon) do not need to acquire more, as they carry a type of X-Antibody that does not disappear from their bodies.
When a digimon carrying the X-Antibody dies and is sent to the Dark Area, a replica of the X-Antibody is usually found there as residual data. Still, all the replicas discovered quickly disappeared. Over time this changed, the X-Antibody, influenced by the strong survival instinct in its carrier's digicore, developed a self-preservation function. Consequently, the replicas of the X-Antibody in the dark area stopped disappearing, and were eventually altered to be able to be ported as if they were normal X-Antibody. These replicas can be supplied to other digimon as a serum, allowing them to undergo an X-Evolution and thus prevent or recover from the X Program. Furthermore, the type of X-Antibody that does not disappear can be obtained by absorbing the data of any digimon that carried it naturally.
- 1 Levels of X-Antibody
- 2 Effects of the X-Antibody
- 3 Death-X-Evolution
- 4 Appearances
- 4.1 Anime
- 4.2 Manga
- 4.3 Video Games
- 4.4 Virtual Pets
- 4.5 TCG
- 5 Image Gallery
Levels of X-Antibody
The effects of this antibody differ depending on the concentration of antibodies present on the Digicore, so in order to tell apart X-Antibody Digimon from regular Digimon, Yggdrasil created the X-Antibody Indicator, a system later implemented on the Pendulum X. There's a total of three levels of X-Antibody:
-First level, Weak (also known as X-Antibody Protoform): At this level, the X-Antibody only grants resistance to the effects of the X Program.
-Second level, Normal: Apart from granting resistance to the X Program, at this level the X-Antibody also has the ability to directly affect the Digicore and extract information on a high degree, thus manifesting a Digimon's proprietties hidden in the deepest part of its Digicore. Therefore, the potential shown by these Digimon does not compare to conventional Digimon of the same level.
-Third level, Strong: A characteristic of the strongest X Digimon.
Effects of the X-Antibody
X-Evolution is the most associated effect to the X-Antibody. This kind of evolution happens when the levels of X-Antibodies reach the second level and the hidden data of the Digimon's Digicore is extracted, changing its appearence. A side effect of this evolution (just like in many others) is that the Digimon also gets healed from its previous wounds, and most of its stamina is recovered.
Since the X-Antibody extracts the hidden data on a Digimon's Digicore, its side effects will also depend on what and how much data there is to extract. Depending on the Digimon, this can create new weapons, upgrade previous ones, grant Digimon new attacks and/or abilities, upgraded armor and even repairing corrupted data on the user's Digicore. However, this also means that if the Digimon in question has already manifested naturally its latent abilities, than the X-Antibody wont have much effect on it, and thus, its appearance won't change much either.
The Death-X-Evolution, also known as "The Evolution of Death" (死の進化), is an old relic of evolutionary research that artificially increases the survival instinct to its limit, causing a Digimon to overcome the very concept of mortality by incorporating other digicores to its own, making the digimon undergo an special type of evolution known as "Death-X-Evolution". Digimon normally cannot access to this kind of evolution on its own, and it can only be triggered by a third party that knows how it works, like Yggdrasil or Grand Dracumon. Currently, there is only three known Death-X-Digimon and a program derived from it. 
Digimon World X is based on the history of the X-Antibody. In the game, the X-Antibody can be used to increase the powers of Digimon as well as objects.