Talk:Metamorphose/@comment-38876330-20190603222414/@comment-38876330-20190604113739

Then the users would have to be pretty good at reducing pain and ensuring that they don't suffer from any health complications, because I will guarantee that whatever calculations they would be using this ability according to would be exceptionally complex and would have to have absolutely zero flaws in them for the user's health and safety.

Remember, they are changing their body's appearance, the structure of their skin and/or bones, and not just messing with the behaviour of their cells. If dislocating your thumb even a little hurts a lot and even cause some complications, then this will cause nightmare pain and health issues unless they are able to do away with it.