Trollskin

Whether it is a blessing from a troll shaman, a genetic anomaly or ancestral trait - your fight or flight response triggers an unprecedented regeneration within you.

At the beginning of your turn in combat, you regain hit points equal to your proficiency bonus as your wounds begin to close and heal at a vastly improved rate.

If you cannot regain any further hit points, your skin begins to develop large callous like grows, you may instead gain the hit points as temporary hit points.