It is a fuuinjutsu that uses a kunai and has three kanji on the handle of it. The kanjis are Fuel, Homing and Detonation. The user infuses fire chakra into the kunai which is the fuel of the whole jutsu. After being thrown the homing kanji kicks in and once in short range of a chakra source that doesn't match the fire chakra, the fire chakra burst out changing directions and propel towards the largest foreign chakra source on the battle field at the time. The changing direction can change three times and used passively. The kunai detonation kanji activates releasing shards of heated kunai pieces. The seal can't be used in wet conditions. It is also used only three times per battle.
I like the jutsu for its usage of weapons or just one weapon. Me being an all range type of rper and loves weapons need more jutsus to my collection I have to stand against the ninjutsu users.