The Heavenly Foot Of Pain may be a cool name for an attack, but as this CBR article highlights, it's also a fancier name for what's known as a jumping or flying ax kick. The beauty of the technique is that essentially gravity, balance, and the heel of the foot are all combining for an impressive attack. This is a technique featured in real-life martial arts like Taekwondo. The main root of the attack is an ax kick. As noted in Taekwondo Nation, when it comes to ax kicks, the goal is to think of the leg swinging down like an ax. The heel is used to come down on either the opponent's head or collarbone. Once the standard ax kick is mastered, the jumping portion of the attack comes into play. And as this Howcast Taekwondo video notes, the key point to remember when adding in jumping is to keep the upper body well-balanced, jump from the back leg, and keep the toes pointed up. Flexibility also helps a lot.
Now, the attack won't leave a crater on the ground or instantly win Hokage status. But if successfully performed, it'll definitely look way cooler than ninja running.
