Augmented Abrasive Dermis

You acquire a coarse, hardened outer layer of skin
called Dermis that is more resistant to heat and
cold. If you would lose health, you instead shed
your Dermis, and prevent that loss of health. If
the health loss your Dermis prevented was the
result of a melee attack, your attacker takes
damage. You automatically grow a new Dermis
by spending an hour out of combat.
(Other Mutations may grant additional
effects of extra layers of Dermis.)