Serpent Form

 You can use an action to polymorph into a Medium snake or back into your true form. Your statistics are the same in each form. Any equipment you are wearing or carrying isn’t transformed. If you die, you stay in your current form.

While in snake form, you gain a bite attack as a natural weapon, which you can use to make unarmed strikes. If you hit with it, you deal piercing damage equal to 1d4 + your Strength modifier, instead of the bludgeoning damage normal for an unarmed strike. When you hit with a bite attack, you can choose to deal 2d6 additional poison damage to the target. Once you deal this poison damage, you can’t do so again until you finish a long rest.