Leifa is Buddhism, and you can practice it with confidence, but it is best to have a regular teacher to pass it on, and it is not recommended to practice it indiscriminately, which is prone to problems. Moreover, practicing thunder is not only an external skill, but also an internal skill, so as to give full play to the effect.
To learn the thunder method, Fu Faqing (Fu Guoqing) from Changsha can consider it.