Cloak of Serpents

A mass of writhing, translucent snakes drapes your body, protecting you from harm and fending off enemies. You can end the spell early by using an action to dismiss it.
For the duration of the spell, you gain resistance to poison damage and immunity to the poisoned condition. In addition, whenever a creature within 5 feet hits you with a melee attack, that creature is struck by one of the serpents. The attacker takes 2d8 poison damage and must succeed on a Constitution saving throw or be poisoned for 1 minute. A successful saving throw halves the damage and negates the poisoned effect.