Fang of the Laughing Prince

Your triumphs in life and battle have lead to a special blessing from the Laughing Prince, or one of his servants.  You have been blessed in the following ways:

• Your Bite attack's damage die increases from 1d6 to 1d8.
• When you hit a creature with your bite attack, the target must succeed on a DC 12 Constitution saving throw or take 7 (2d4) poison damage.  
• When you reduce a creature to 0 hit points with a critical hit, you can use your Rampage feature without expending a use of it.