Kesshoton (血漿遁 lit. Plasma Release) is the unique combination of fire and lightning chakra. This is the preferred style of Hayashi Kakgekyo. The unity of both fire and lightning gives every technique extreme heat, in which lies it’s combat potential and sheer killing ability. If there are any other users, it is currently unknown.
Even though this is quite possibly over-powered, there are a fair number of weaknesses to counter it. The most obvious is water or ice to cool it off and thereby removing the brunt of the destructive force. You could also use earth to create a good defense against it, while wind, in some cases, could virtually deflect it.