1. Hachimon Tonkou: The most powerful physical technique in the ninja world, Hachimon Tonkou, requires unlocking the eight gates through strict and harsh training.

2. Shishijyutsu Henka: After joining the Akatsuki, Hidan learned Shishijyutsu Henka, a jutsu that allows him to share his pain with others. 

3. Gedo Mazo: Gedo Mazo, the vessel of the Ten-Tails, can be summoned and controlled by those with the Rinnegan. However, it requires sacrificing one's body and enduring the insertion of black rods as a source of chakra. 

4. Shikotsumyaku: The bone manipulation ability of the Kaguya clan, Shikotsumyaku, allows users to freely manipulate their bones for offense and defense. However, mastering this ability involves the pain of bone extraction.

5. Chakra Scalpel: However, the mastery of this technique leaves Karin's body covered in bite marks, symbolizing the pain and cruelty involved.