You increase your Constitution or Wisdom score by 1.

When the chips are down, and everything looks bleak, you rise to the occasion and excel!  The forces of the universe are seemingly on your side.

The harder a task is, and the less likely your chances to achieve that task, the better your chances of actually pulling it off!  Once per short rest, you can re-roll an ability or skill check you just failed, but on the second roll, the DC of the check is 15.