As an action, make a melee weapon attack with a natural weapon that deals poison damage.

On a hit, add the stamina die to the attack’s poison damage and the creature must succeed on a Fortitude saving throw against poison (Difficulty equal to 9 + your Constitution + your Aptitude Bonus) or become poisoned for the duration.

On a critical hit, add twice as much damage.

On a miss by 4 or less, add half as much damage.

The creature can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success.

Enhance

You can increase the damage for each additional stamina die expended.