Rune Carver's Defense

You have discovered a rune that raises natural defenses by toughening your flesh and hardening your skin until it is on par with a Hill Giant. When etched into your body, it grants the following abilities:

• Increase your Strength or Constitution score by 1, to a maximum of 20.
• While you aren’t wearing armor, you can calculate your AC as 13 + your CON modifier. You can use a shield and still gain this benefit.