Blood Bound Fortitude

You have learned how to extract power for a cost, a blood ritual only able to be performed once in a beings life. The sacrifice for a great power is one of great risk, through your will you brave the deadly challenge of surviving this blood transmutation, but at the cost of losing two points to either your Strength, Dexterity, or Constitution score.

Through this ritual the price you have paid gives you the following benefits: 

• Your hit dice increase by one stage, a d6 -> d8, a d8 -> d10, and a d10 -> d12
  
  
• You may as an action regain a hit die. You can use this feature a number of times equal to your proficiency bonus, and you regain all expended uses of it when you finish a long rest.
  
  
• Finally, your fortitude thickens, while you are not wearing armor you gain +1 to your AC.