"Disaster Force" (ディザスターフォース Dizasutāfōsu) is an ability that was discovered by Kyoya Gaen.
Disaster Force's main use is the ability to turn the power of the cards real, and it can be activated with a Dark Core Deck Case. When activated, the user's hair becomes longer and its influence can make the user malevolent and power addicted should they be unable to handle its influence.
In addition, Disaster Force can provide other abilities that can vary depending on the user, such as Sofia's Psychic powers and Kiri's Ice powers.
As displayed in episode 50, it appears that the power of Disaster Force can activate against a user's will, if they are not focused solely on the task at hand. This is seen when Rouga, upset at Kyoya Gaen's scheming with the Purgatory Knight, temporarily lost control over his Dark Core Deck Case and unleashed Disaster Force twice.
Unlike its heroic counterpart - Future Force, Disaster Force can be used anywhere, even in the far future where the Future Force cannot be used.
It is explained by Kyoya Gaen, that the Disaster Force is created by utilizing spatial rifts that are created when Buddyfight cards link the player to parallel Worlds. By harnessing this fact, a Dark Core Deck Case can cause the effects and power of the cards to become real, and can also allow for the opening to parallel worlds, such as Darkness Dragon World.
A similar ability, Future Force, created by the Buddy Police exists, and according to Kyoya Gaen, it is actually the same as Disaster Force. However, as revealed in Episode 64, despite the similarities in their uses, they are two distinct powers, with Future Force being powered by the potential of the future.
During the Gaen Cup, Disaster's Force was revealed when Rouga lost control of it. At the same time, Kyoya claimed that Disaster Force was "accidentally discovered" by his researchers, though Asmodai quickly noticed that it was a cover story to prevent losing credibility in front of the audience.
Before the Gaen Cup final, Sofia was giving away a large amount Dark Core replicas to kids so they can all use Disaster Force. In the middle of the fight between Gao and Tasuku, a gate leading to Darkness Dragon World was opened allowing Great Evil Dragon, Samael Apocalypse to appear. This also allowed Kyoya to reveal an upcoming invasion from Darkness Dragon World and convince the audience that Disaster Force can be used to stop it so he hosted the Gaen Cup to recruit kids to "fight to save the world". In reality, using Disaster Force is what fuels the gates, and Kyoya used his charisma and manipulation to make himself look like a savior to the world.
When Kyoya's plan was stopped all the Dark Core replicas were destroyed, however normal Dark Cores are still fully operational and can still use Disaster Force as usual.