Vine Suit

You wrap your body in a thicket of vines. You gain 20 temporary hit points. While you have these hit points you gain resistance to bludgeoning damage and whenever a creature hits you with a melee attack you can use your reaction to attack them with the vines making a melee spell attack and dealing 1d8 + your spellcasting modifier bludgeoning damage.

You gain an additional 10 hit points for every level spell slot above 2nd