This move is the strongest move in Katsuki's arsenal, which involves Katsuki taking to the air, and then using explosions to propel himself in a circular motion to create a tornado. The ensuing twister collects oxygen and momentum to fuel the subsequent explosion.
Katsuki releases the enhanced, aforementioned blast upon impact with the ground. The technique and its effectiveness are comparable to that of a missile. It was first used in Katsuki's match with Shoto Todoroki during the U.A. Sports Festival. It had enough destructive force to completely destroy Shoto's Heaven-Piercing Ice Wall. He has also shown that he can release the fueled explosion in midair, without having to make contact with the target.
Howitzer- Wikipedia article on the weapon the attack is named after