User is able to make their skin like steel.

Pros:
-user can do the same to their bones
-user has super strength
-user can do this volunteerly
-user can change skin of others

Cons:
-user becomes heavier
-user can swim when quirk is active
-user can't control their strength
-user's skin will rust if changed for too long

Weakness: extreme heat
User will melt gradually when near extreme heat