The most dangerous kick in martial arts is the roundhouse kick. This is why Muay Thai has become the preferred stand up modality for many MMA fighters. Muay Thai allows for elbows, knees, spinning back kicks and roundhouse kick.
To know more about Muay Thai roundhouse kick, check out this video by HowcastSportsFitness:
Why is the Muay Thai Roundhouse Kick so Effective and Powerful?:
Mixed martial arts workouts and training are must for any fighter in leading up to a contest. Roundhouse kick requires overall rotation of your bodies when kicking. This kick produces ample force by transferring weight and making a connection with the ground. For this your right hip should fully rotate over the left hip when you swing your body. Once you have made contact, bring your leg back the same way you cam in, try to do this quickly.