Tenacious

Tenacious:

Hardy and resilient, you gain the following benefits:

• Increase your Constitution score by 1, to a maximum of 20.
• When you roll a Hit Die to regain hit points, the
  minimum number of hit points you regain from the roll equals twice your Constitution modifier (minimum of 2).
• Your hit point maximum increases by an amount equal to twice your level when you gain this feat. Whenever you gain a level thereafter, your hit point maximum increases by an additional 2 hit points.