The body refining techniques of Shaolin Temple are already quite well-known, and there are at least dozens of them in total, among which the Vajra Immortal Technique, although sounding quite domineering, is a cultivation method many people choose to learn.
However, the technique is popular because a great number of people choose to cultivate it, but cultivating it to Great Achievement is not so easy.
The entry to the technique is pretty simple, but to cultivate it to Great Achievement, one needs a great deal of willpower.
Therefore, when choosing techniques, few of the Shaolin Temple's martial monks, who possess decent talent, choose to cultivate this Vajra Immortal Technique, because if they fail, they would basically have wasted all their efforts.
To be honest, the Vajra Immortal Technique that hasn't reached Great Achievement isn't that strong.