Natural Weapon Master

You've learned to attack with animal ferocity. You gain the following benefits:

• On your turn, when you score a critical hit with a natural weapon or reduce a creature to 0 hit points with one, you may regain hit points equal to your constitution modifier.
• Before you make a melee attack with a natural weapon that you are proficient with, you can choose to take a -5 penalty to the attack roll. If the attack hits, you add +10 to the attack's damage roll.