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Mist Dispersion (ミスト・ディスパージョン) is an undisputed A rank destructive Decomposition spell that directly decomposes the physical structure of the information targeted. It works on inanimate objects as well as living organisms. It can decompose muscles, tissue, bone, even organs into the basic molecules such as ions and the basic elements by interfering with the structural information. It is described as being considerably mundane and quiet. There is no sound or light emitted and when raised to the highest degree of Decomposition, even easily flammable materials will not ignite. The objects dissipate to dust, transform into steam and then scatter. This spell does not travel through physical space so it can be aimed through physical objects and is not limited by distance by any means.
Mist Dispersion is also called Vanishing Clouds, Fog Dispersal, Demon Right. Direct interference into the structural information of an object is a form of magic of the highest difficulty. 
Like Gram Dispersion, Mist Dispersion also "decomposes" structural information, but the basic difference between the two is Gram Dispersion "decomposes" structural information in the 'Idea Dimension' (i.e. Psion structure - Magic Sequences and Activation Sequences) while Mist Dispersion "decomposes" structural information in the 'Physical Dimension/World'. It is a classified magic.
This is the only known counter to Yotsuba Maya's Meteor Stream, which manipulates the physical properties of light to drill holes in any object. Anything that the light ray touches, including Phalanx, the magical barriers of the Juumonji Family, is immediately pierced. Tatsuya's Mist Dispersion, however, can directly decompose the structure of light itself, preventing the light ray from passing through anything.
Despite Mist Dispersion's dominance over Meteor Stream (which made Maya renown for being the strongest magician in the world), there are several methods of countering Mist Dispersion. Coincidentally, the first way is the defensive spell Phalanx, as it creates multiple barriers behind one another that continually regenerate. These barriers also protect the caster's personal information, making it difficult for the spell to be aimed directly through the barrier. While Phalanx is not necessarily a true weakness of Mist Dispersion, Mist Dispersion cannot easily break down the entire set of continually regenerating magical barriers. A battle involving Phalanx and Mist Dispersion would be one of attrition and endurance between regeneration of the barrier and dissolution of the barriers. The second counter is Contact-Type Gram Demolition. It creates a formless armor of Psions around the body that also protects the caster's personal information in the Information Dimension. The third counter is using strong camouflaging or sensory interference type magics like Matoi, Parade or Ghost Walker. These prevent target acquisition thus blocking Mist Dispersion.
- Trident: The name for the triple Decomposition spell programmed into the CAD of the same name (Silver Horn-custom Trident) that consists of three processes built into one Magic Sequence. The first process decomposes the Wide Area Interference to allow the magic to work without hindrance, the second decomposes the Data Fortification of the target, and the third processes Mist Dispersion to decompose the target. When used it looks as if the target is consumed by static before turning into dust, and the combustible elements burn after reacting with oxygen in air. This magic is often called "Demon Right".
Partial Decomposition (Partial Mist Dispersion)
Tatsuya also uses the magic to partially break down structures or human flesh to either immobilize humans (or cause injuries) or to disable the functioning of objects on single or multiple targets or as area of effect magic.
Tatsuya used this magic to destroy the door of the special reading room to reach the Blanche terrorists (who were accompanied by Mibu Sayaka) trying to steal magic research data from First High. He also used it to destroy the guns of Blanche terrorists during his confrontation with Tsukasa Hajime and later used it under the effects of Cast Jamming by Antinite to injure and immobilize them. 
Deep Mist Dispersion
- Deep Mist Dispersion (ディープ・ミスト・ディスパージョン): A Decomposition Magic which decomposes substances into electrons, protons, and neutrons by interfering with the structures information of the substance deeper than that of Mist Dispersion. It was produced as a prototype in the development process of Baryon Lance, but Tatsuya thought that the burden is too great that it couldn't be used in combat.