Command T (コマンドＴ Komando Tī) is a Caster Magic that allows the user to alter mass and proportions.
Command T is a Magic that allows the user to alter mass, lest it be expansion or reduction; the user can direct the effects of their Magic towards virtually whatever they desire, allowing them to affect, for example, landmass in such a way that it becomes the size of a mountain, or the size of a small boulder. Humans (and other living species and the user) are also susceptible to this particular form of Magic, and can either be expanded to titanic proportions or be shrunk to minuscule sizes, however, in the case of the latter, to onlookers not aware of this Magic's effects, the act of reduction can appear one of disintegration. The acts of expansion and reduction can also be isolated to specific body parts.
The Magic's usefulness also extends to expanding the size of weaponry, turning a dagger into a fearsome sword, and even to first-aid, allowing the user to locate, once isolated, life-threatening internal masses and shrink them to negligent sizes. Physical, life-threatening injuries are also able to be tended to, and they can be reduced in size until they are a non-factor. Even other types of Magic can be reduced and compressed, and then fired back at the original caster as a magnified weapon. Lastly, this Magic can be used as a means of quick assassination, as the user can cause internal organs to swell until they rupture.
Limits, however, do exist to Command T: people are able to completely resist this Magic if they are of a certain caliber of strength, as Neinhart was completely unaffected by original caster Brandish μ's attempt to re-shape him following his immense power increase by Irene Belserion. This was later confirmed by Brandish herself, who said that she was no longer able to shrink the mysterious mass inside Natsu's body as the power it gave him transcended her own.