After being horribly burnt all over his body after an out-of-control blaze he started at a chemical factory, he designed and built an insulated, fire-retardant battlesuit to not only protect himself, but outfit it with a number of different features, most of which relate to incendiary weaponry.
Using the power of a ring and a glove that contain special powers, Tsuna is capable of using the Dying Will Flame (when using pills or boosters) which is a form of high pressure energy that has destructive powers and can purify evil auras.
He is a mutant who has the psionic ability to manipulate flame by shaping it as he desires, increasing or decreasing its heat, intensity, and size. He cannot actually create fire himself, however, and consequently wears a specially insulated costume with a built-inflamethrower that can throw a stream of flame a maximum distance of 25 feet (7.6 m). He can psionically manipulate the flame to do whatever he desires, and sometimes induces it to take semi-solid form as an animate flame being (these creations, though capable of movement and of grasping or carrying solid objects, are not alive and do not think or act on their own).