Kaio-ken

Kaio-ken (界王拳; lit. "Fist of the World King" or "World King Fist") is a fighting technique discovered and coveted by Honō Uzumaki and is one of the only people physically and mentally strong enough to preform the technique. It is a technique that multiplies the user's chakra, power, their whole being; for a "heart beat".

Description
As a result of the Kaio-ken, the user's base chakra, strength, speed, and senses greatly increase for an instant or as long as the technique is being channeled and used. Hono has demonstrated the ability to heighten the effect of the Kaio-ken to increasingly higher multiplications. This enables the user to inflict serious damage to opponents who are considerably stronger than them dependent on how far one wishes to push Kiao-ken. The dead give away of this ability is that the user's aura color becomes crimson and radiates heat.

Rates of power vary on the limitations of the user.

After first mastering the Kaio-ken, the furthest Hono could handle was the Kaio-ken x4. At this point, Hono's muscles began to dissolve from the sheer force and power that he wasn't able to keep under control. In the end, the power swallowed him, leaving him as a vegetable for many months before his body was recuperated. Wanting to strength himself, he used his Uzumaki Clan's Hiden Kekkei Genkai Dark Ecriture he scribbled seal after rune after inscription cause the gravity pounding down on him to multiple. Eventually, through training this way, his muscles built up huge strength and resistance allowing him to withstand astounding multiplications of the Kaio-ken technique, such as Kaio-ken x10 or even x20 Though, x10 is the furthest Hono has gone without sub coming to exhaustion.

The technique, however, has its substantial flaws. If the user multiplies their base power too much, the up-rise of chakra and power could easily obliterate them, or severely damage their body, as it Hono has witnessed first hand. A victories slap on the back from a gracious friend post-battle would feel worse then having a planet drop on you. To a point, one can surpass the Eight Gates in power and strength but only at a massive cost. Even ones life.