Lockjaw

You know the one great truth about being a goblin: once you bite, you don't let go.  You gain the following benefits:

• Increase your Strength or Dexterity score by 1, to a maximum of 20.
• Your teeth become natural weapons.  They deal 1d6 piercing damage on a hit and have the finesse property, and you can grapple using your jaws.  While grappling in this way, you cannot speak or cast spells with verbal components, and you cannot use your jaws to attack any creature except the one you are grappling.
• You have advantage on melee weapon attacks against grappled creatures.